Field-induced Spin Reorientation Research Articles

Manipulation of anisotropic Zhang-Rice exciton in NiPS3 by magnetic field

The effect of external magnetic fields on the behavior of the Zhang-Rice exciton in NiPS3, which captures the physics of spin-orbital entanglement in 2D XY-type antiferromagnets, remains unclear. This study presents systematic study of angle-resolved and polarization-resolved magneto-optical photoluminescence spectra of NiPS3 in the Voigt geometry. We observed highly anisotropic, non-linear Zeeman splitting and polarization rotation of the Zhang-Rice exciton, which depends on the direction and intensity of the magnetic field and can be attributed to the spin-orbital coupling and field-induced spin reorientation. Furthermore, above the critical magnetic field, we detected additional splitting of the exciton peaks, indicating the coexistence of various orientations of Néel vector. This study characterizes orbital change of Zhang-Rice exciton and field-induced spin-reorientation phase transitions in a 2D hexagonal XY-type antiferromagnet, and it further demonstrates the continuous manipulation of the spin and polarization of the Zhang-Rice exciton.

Magnetic-field-induced spin reorientation in TmFeO<sub>3</sub> single crystals

TmFeO<sub>3</sub> exhibits rich physical properties such as magneto-optical effect, multiferroicity, and spin reorientation, making it possess significant research value in condensed matter physics and materials science. In this study, we utilize a time-domain terahertz magneto-optical spectroscopy system to investigate the changes in spin resonance frequency of TmFeO<sub>3</sub> single crystal at <i>T</i> = 1.6 K under external magnetic fields in a range of 0–7 T. The TmFeO<sub>3</sub> sample is grown in an optical floating zone furnace and its crystallographic orientation is determined by using back-reflection Laue X-ray photography with a tungsten target. The measurement setup is a self-built time-domain terahertz magneto-optical spectroscopy system, with magnetic fields in a range of 0–7 T, temperatures in a range of 1.6–300 K, and a spectral range of 0.2–2.0 THz. A pair of 1 mm-thick ZnTe nonlinear crystals is used to generate and detect terahertz signals through optical rectification and electro-optic sampling technique. The system variable temperature and magnetic field are controlled by a superconducting magnet. In experiments, a linearly polarized terahertz wave is vertically incident on the sample surface, and its magnetic component <i>H</i><sub>THz</sub> is parallel to the sample surface. By rotating the sample, the angle (<i>θ</i>) between macroscopic magnetic moment <i> <b>M</b> </i> and <i>H</i><sub>THz</sub> can be tuned, achieving selective excitations of the two modes, that is, <i>θ</i> = 0 for q-AFM mode and 90° for q-FM mode. Terahertz absorption spectrum results indicate that as the magnetic field increases, the quasi-ferromagnetic resonance (q-FM) of TmFeO<sub>3</sub> single crystal shifts towards high frequencies, and quasi-antiferromagnetic resonance (q-AFM) transits to q-FM under low critical magnetic fields (2.2–3.6 T). Through magnetic structure analysis and theoretical fitting, it is confirmed that the magnetic moment of the single crystal undergoes magnetic field induced spin reorientation. This study is helpful in better understanding of the regulation mechanism of the internal magnetic structure of rare earth ferrite under the combined action of external magnetic field and temperature field, and also in developing related spin electronic devices.

Crystal growth of CeMn0.85Sb2: Absence of magnetic order of Ce-sublattice

Single crystals of CeMn0.85Sb2 have been successfully synthesized by using the Bi as flux. Analysis of single crystal x-ray diffraction data confirms that CeMn0.85Sb2 crystallizes in the HfCuSi2-type structure with the space group P4/nmm (No. 129). In the case of H||c, CeMn0.85Sb2 displays a robust antiferromagnetic transition at ∼160 K for Mn-sublattice, and there is no sign of magnetic order regarding Ce-sublattice. In the case of H ⊥ c, the Mn-sublattice shows signs of magnetic order at 160 K and 116 K, indicating a possible spin reorientation. There is no sign of magnetic order for the Ce-sublattice either, but, alternating current magnetic susceptibility measurements reveal a spin glass state below 18 K in the case of H ⊥ c. Isothermal magnetization curves measured below magnetic order with H ⊥ c show saturation and even large hysteresis at 2 K, indicating the presence of a ferromagnetic component. In addition, a field-induced spin-flop transition is observed in the case of H ⊥ c, indicating a field-induced spin reorientation of Mn spins. Electrical resistivity measurements indicate a metallic nature for CeMn0.85Sb2 and large anisotropy which is consistent with its quasi-two-dimensional layered structure.

Field-induced spin reorientation in the Néel-type antiferromagnet MnPS3

Manipulation of spin orientation in magnetic material has been the focus of increasing research interest, as it brings fascinating perspectives with regard to the exploration of underlying magnetic interactions and the design of electronic devices. Here we report on the field-induced spin reorientation below N\'eel temperature in antiferromagnet ${\mathrm{MnPS}}_{3}$. The ferromagnetic ordering emerges in the antiferromagnetic phase in ${\mathrm{MnPS}}_{3}$ at temperatures below $\ensuremath{\sim}34$ K with external magnetic fields up to $\ensuremath{\sim}2$ kOe. Such a coexistence of the ferromagnetic and antiferromagnetic phases is obtained in both perpendicular $(H\ensuremath{\perp}ab)$ and parallel $(H//ab)$ configurations, even with strong anisotropy. The $H\text{\ensuremath{-}}T$ phase diagram for ${\mathrm{MnPS}}_{3}$ single crystal is further established with multiple magnetic phases being demonstrated. A phenomenological picture of the evolution of spin reorientation under external magnetic fields is proposed as physical insight into the rich magnetic properties of ${\mathrm{MnPS}}_{3}$. Our findings examine an exciting frontier in fundamental investigations of low-dimensional antiferromagnets and open a path towards the realization of conceptual electronic devices.

Insight into the negative magnetization and anomalous exchange-bias in DyFe5Al7 through neutron depolarization and neutron diffraction studies

We have provided the mesoscopic and microscopic understandings of polarity reversal of the magnetization or negative magnetization (NM) below T COMP = 93 K in an exotic magnetic material containing three magnetic sublattices, viz., DyFe5Al7 crystallizing in ThMn12 structure, using neutron depolarization and neutron diffraction techniques. A full recovery of the neutron beam polarization at the T COMP in a neutron depolarization experiment reveals a total compensation of magnetization inside the magnetic domains in the sample. The temperature-dependent neutron diffraction study under zero magnetic field has provided temperature dependencies of antiparallelly coupled Dy (M Dy(2a)) and Fe (M Fe(8f) and M Fe(8j)) sublattice magnetic moments along [100] direction. The dominance of |M Dy(2a)| over total Fe moment, , below T COMP leads to the NM in the compound. The magnetization versus magnetic field curves below the T COMP indicate the presence of field-induced spin reorientation in the compound. The magnetic field required for spin reorientation (H SR) is maximum at the lowest temperature and it decreases to zero as the temperature is increased to T COMP. Interestingly, the compound shows a finite exchange-bias (H EB) below the T COMP only, as evident from the field-cooled hysteresis loops, while at T > T COMP, H EB is almost zero. The cooling-field (H COOL) dependent study of H EB shows a slope change at H COOL ∼ H SR indicating a correlation of exchange-bias with spin-reorientation in the compound. This study, apart from revealing microscopic understanding of magnetic behavior of an exotic three magnetic sublattice system, provides a correlation among exchange-bias, magnetic compensation, and spin-reorientation phenomena.

Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains

Easy axis antiferromagnets are robust against external magnetic fields of moderate strength. Spin reorientations in strong fields can provide an insight into more subtle properties of antiferromagnetic materials, which are often hidden by their high ground state symmetry. Here, we investigate theoretically effects of curvature in ring-shaped antiferromagnetic achiral anisotropic spin chains in strong magnetic fields. We identify the geometry-governed helimagnetic phase transition above the spin-flop field between vortex and onion states. The curvature-induced Dzyaloshinskii-Moriya interaction results in the spin-flop transition being of first- or second-order depending on the ring curvature. Spatial inhomogeneity of the N\'eel vector in the spin-flop phase generates weak ferromagnetic response in the plane perpendicular to the applied magnetic field. Our work contributes to the understanding of the physics of curvilinear antiferromagnets in magnetic fields and guides prospective experimental studies of geometrical effects relying on spin-chain-based nanomagnets.

Disappearance of spiral spin order and field induced spin reorientation transition in Fe[formula omitted]Cr[formula omitted]VO[formula omitted] (0.1[formula omitted][formula omitted][formula omitted]0.3) multiferroic: 57Fe Mössbauer spectroscopic studies

Here we report a progressive suppression of spiral spin order and evidence for disappearance of spin reorientation transition (SRT) in Fe1−xCrxVO4 (0.1 ≤x≤ 0.3) studied by low temperature and high magnetic field (LTHM) Mössbauer spectroscopy (MS). Variation in the area ratio of lines 2 and 3 (A23) with external magnetic field confirms the presence of antiferromagnetic (AFM) ordering for all the compositions at the lowest temperatures (5 K). Field induced spin reorientation transition is being observed in both triclinic (x = 0.10) and mixed phase (x = 0.175) systems, evidenced by the change in the sign of quadrupole shift (QS) value at low temperatures, where as the SRT is absent in the monoclinic phase (x = 0.20 and 0.30). MS line width (Γ) values indicate the presence of spiral spin order in T-phase, partial suppression in mixed phase (T + M) and finally complete suppression for the M-phases.

High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH4)2[FeCl5·(H2O)

We combine high field polarization, magneto-infrared spectroscopy, and lattice dynamics calculations with prior magnetization to explore the properties of (NH4)2[FeCl5·(H2O)]─a type II molecular multiferroic in which the mixing between charge, structure, and magnetism is controlled by intermolecular hydrogen and halogen bonds. Electric polarization is sensitive to the series of field-induced spin reorientations, increasing linearly with the field and reaching a maximum before collapsing to zero across the quasi-collinear to collinear-sinusoidal reorientation due to the restoration of inversion symmetry. Magnetoelectric coupling is on the order of 1.2 ps/m for the P∥c, H∥c configuration between 5 and 25 T at 1.5 K. In this range, the coupling takes place via an orbital hybridization mechanism. Other forms of mixing are active in (NH4)2[FeCl5·(H2O)] as well. Magneto-infrared spectroscopy reveals that all of the vibrational modes below 600 cm-1 are sensitive to the field-induced transition to the fully saturated magnetic state at 30 T. We analyze these local lattice distortions and use frequency shifts to extract spin-phonon coupling constants for the Fe-O stretch, Fe-OH2 rock, and NH4+ libration. Inspection also reveals subtle symmetry breaking of the ammonium counterions across the ferroelectric transition. The coexistence of such varied mixing processes in a platform with intermolecular hydrogen- and halogen-bonding opens the door to greater understanding of multiferroics and magnetoelectrics governed by through-space interactions.

Spin mapping of intralayer antiferromagnetism and field-induced spin reorientation in monolayer CrTe2

Intrinsic antiferromagnetism in van der Waals (vdW) monolayer (ML) crystals enriches our understanding of two-dimensional (2D) magnetic orders and presents several advantages over ferromagnetism in spintronic applications. However, studies of 2D intrinsic antiferromagnetism are sparse, owing to the lack of net magnetisation. Here, by combining spin-polarised scanning tunnelling microscopy and first-principles calculations, we investigate the magnetism of vdW ML CrTe2, which has been successfully grown through molecular-beam epitaxy. We observe a stable antiferromagnetic (AFM) order at the atomic scale in the ML crystal, whose bulk is ferromagnetic, and correlate its imaged zigzag spin texture with the atomic lattice structure. The AFM order exhibits an intriguing noncollinear spin reorientation under magnetic fields, consistent with its calculated moderate magnetic anisotropy. The findings of this study demonstrate the intricacy of 2D vdW magnetic materials and pave the way for their in-depth analysis.

Spin structure at zero magnetic field and field-induced spin reorientation transitions in a layered organic canted antiferromagnet bordering a superconducting phase

We attempted to assign the spin structure of a layered organic antiferromagnet, $\ensuremath{\kappa}$-(d8-BEDT-${\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{Br}$, which is a key material located closest to the Mott boundary at ambient pressure among this family of compounds, by investigating its macroscopic magnetization thoroughly, motivated by a recent successful assignment of the spin structure of an isostructural material, $\ensuremath{\kappa}$-(BEDT-${\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{Cl}$ [BEDT-TTF and d8-BEDT-TTF are bis(ethylenedithio)tetrathiafulvalene and its deuterated molecule, respectively]. We measured the isothermal magnetization after careful choice of the measurement temperatures and cooling speed at around 80 K, so that the magnetism of the antiferromagnetic phase can be effectively extracted. Consequently, we observed hysteresis loops signifying ferromagnetism and steplike behavior when the magnetic field applied parallel to the crystallographic $b$ and $a$ axes was swept, respectively. The possible spin structure consistent with these results was discussed in terms of probable interactions between the spins, such as exchange interactions and the Dzyaloshinskii-Moriya interaction. Eventually, we asserted that $\ensuremath{\kappa}$-(d8-BEDT-${\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{Br}$ has a spin structure with the easy axis being the $c$ axis and the net canted moment parallel to the $b$ axis, which is surprisingly different from that of $\ensuremath{\kappa}$-(BEDT-${\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{Cl}$. We suggested that this difference originates from the difference of the sign of the interlayer interaction between the two materials. We also elucidated the overall picture of the magnetization processes of this material under the magnetic fields parallel to the three principle axes, which are also in contrast to those of $\ensuremath{\kappa}$-(BEDT-${\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{Cl}$. In particular, the spin-reverse transition at which half of the spins rotate by ${180}^{\ensuremath{\circ}}$ was not induced by the $b$-axis magnetic field, as in the case of $\ensuremath{\kappa}$-(BEDT-${\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{Cl}$, but by the $a$-axis magnetic field. Finally, numerical simulations and magnetic symmetry analysis enabled us to confirm the validity of the spin structures proposed for the two antiferromagnets under zero and high magnetic fields.

Quaternary intermetallics RE 2Pt3Ga4In (RE=Y, Gd-Tm) – intergrowth structures of NdRh2Sn4 and TiNiSi related slabs

Abstract The quaternary gallium-rich intermetallic phases RE 2Pt3Ga4In with RE = Y and Gd-Tm were synthesized by arc-melting of the elements and subsequent annealing. Small single crystals were obtained by high-frequency annealing of the samples in sealed tantalum ampoules. The polycrystalline samples were characterized through their X-ray powder patterns. The RE 2Pt3Ga4In phases crystallize with a site ordering variant of the orthorhombic Y2Rh3Sn5 type, space group Cmc 21. The structures of Gd2Pt3Ga4In, Dy2Pt3Ga4.14In0.86, Er2Pt3Ga4.17In0.83 and Tm2Pt3Ga4.21In0.79 were refined from single-crystal X-ray diffraction data. The single crystals reveal small homogeneity ranges RE 2Pt3Ga4±xIn1±x. The striking geometrical structural building units are slightly distorted trigonal prisms around the three crystallographically independent platinum atoms: Pt1@RE 4Ga2, Pt2@RE 2Ga4 and Pt3@RE 2Ga2In2. Based on these prismatic building units, the RE 2Pt3Ga4In structures can be described as intergrowth variants of TiNiSi and NdRh2Sn4 related structural slabs. Temperature dependent magnetic susceptibility studies of Gd2Pt3Ga4In and Tb2Pt3Ga4In show Curie-Weiss behavior and the experimental magnetic moments confirm stable trivalent gadolinium respectively terbium. Gd2Pt3Ga4In and Tb2Pt3Ga4In order antiferromagnetically at T N = 15.8(1) and 26.0(1) K. Magnetization curves at 3 K show field-induced spin reorientations.

Terahertz spectroscopy study of doping and magnetic field induced effects on spin reorientation in Ho<sub>1–<i>x</i></sub>Y<sub><i>x</i></sub>FeO<sub>3</sub> single crystals

In this paper, the effects of magnetic field and nonmagnetic Y<sup>3+</sup> doping on spin state and spin reorientation in HoFeO<sub>3</sub> single crystal are systematically studied by the self-developed terahertz time-domain spectroscopy (THz-TDS) under magnetic field. By doping nonmagnetic Y<sup>3+</sup>, we find that the spin reorientation temperature range decreases. Meanwhile, we also find the type of spin reorientation of HoFeO<sub>3</sub> does not change with Y<sup>3+</sup> doping, indicating that the Y<sup>3+</sup> doping can exchange the interaction energy of Ho<sup>3+</sup>-Fe<sup>3+</sup> without introducing any new magnetic structure. Moreover, the resonance frequency of quasi-ferromagnetic mode (q-FM) decreases with temperature increasing in the low temperature range, while the resonance frequency of quasi-antiferromagnetic mode (q-AFM) increases with temperature increasing in the high temperature range in Ho<sub>1–<i>x</i></sub>Y<sub><i>x</i></sub>FeO<sub>3</sub> single crystals. With the external magnetic field (<i> <b>H</b> </i><sub>DC</sub>) applied along the (110) axis, on the one hand the magnetic field can not only tune the resonant frequency of q-FM but also induce the spin reorientation in Ho<sub>1–<i>x</i></sub>Y<sub><i>x</i></sub>FeO<sub>3</sub> single crystals, and on the other hand this magnetic field induced spin reorientation phenomenon can happen more easily if the temperature approaches to the intrinsic spin reorientation temperature range of the single crystals. Besides, the critical magnetic field induced spin reorientation increases with the doping of Y<sup>3+</sup> increasing. Our research shows that THz spectroscopy data can be used to detect the doping concentration of Y<sup>3+</sup> ions in HoFeO<sub>3</sub>; in addition, Y<sup>3+</sup> doping can make the spin state in HoFeO<sub>3</sub> crystal more stable and not easily affected by external magnetic fields. We anticipate that the role of doping and magnetic field in spin reorientation transition will trigger great interest in understanding the mechanism of the spin exchange interaction and the mechanism of external field tuning effect in the vast family of rare earth orthoferrites.

Magnetic behavior and complete high-field magnetic phase diagram of the orthoferrite ErFeO3

Magnetic transitions in a single crystal of the orthoferrite ${\mathrm{ErFeO}}_{3}$ have been studied between 2 and 300 K using conventional superconducting quantum interference device measurements as well as pulsed high magnetic fields of up to 58 T. Spontaneous spin reorientations, as well as temperature and magnetic field induced spin reorientations, have been observed. At spin-reorientation transition temperatures, the ${\mathrm{Fe}}^{3+}$ sublattice exhibits a ${\mathrm{\ensuremath{\Gamma}}}_{4}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Gamma}}}_{2}$ transition where the magnetic coupling between the net magnetic moment of ${\mathrm{Fe}}^{3+}$ $3d$ and ${\mathrm{Er}}^{3+}$ $4f$ is antiferromagnetic, and the temperature dependence of the magnetization suggests that the order of magnitude of the interaction is ${J}_{\text{Er-Er}}l{J}_{\text{Er-Fe}}l{J}_{\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Fe}}$. However, the magnetic coupling varies widely with temperature and/or magnetic field, which indicates that the ${\mathrm{Er}}^{3+}$ sublattice moment cannot be simply explained by the partial polarization of the paramagnetic spins due to the combination of the molecular field from the net ${\mathrm{Fe}}^{3+}$ moment and external applied magnetic fields. It is found that in a sufficiently high magnetic field, the magnetic interactions between the ${\mathrm{Fe}}^{3+}$ sublattice and the ${\mathrm{Er}}^{3+}$ sublattice are destroyed. Based on the detailed magnetization measurements, the complete high-field magnetic phase diagram has been obtained, providing an important framework for future investigations into the complicated magnetic interactions and magnetoelectric couplings in rare earth orthoferrites.

Magnetolattice coupling, magnetic frustration, and magnetoelectric effect in the Cr-doped FeVO4 multiferroic material and their correlation with structural phase transitions

A detailed account of magnetolattice coupling, magnetic frustration, and magnetoelectric effects in ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{VO}}_{4}$ ($x=0\ensuremath{-}1.0$) studied by temperature-dependent synchrotron x ray diffraction (SXRD), temperature- and magnetic-field-dependent dielectric permittivity $\ensuremath{\varepsilon}$, and magnetization measurements are presented in this paper where progressive Cr doping leads to structural transitions from triclinic (T)---monoclinic (M)---orthorhombic (O) symmetries. SXRD data shows an intricate relationship between magnetic, ferroelectric, and lattice degrees of freedom in these systems. ${\mathrm{FeVO}}_{4}$ reaches a magnetically ordered state with two successive antiferromagnetic orderings at ${\mathrm{T}}_{N1}$ (21.85 K) and ${\mathrm{T}}_{N2}$ (15.65 K), having collinear and noncollinear natures, respectively, as evidenced in DC magnetization measurements. Progressive ${\mathrm{Cr}}^{3+}$ incorporation at the ${\mathrm{Fe}}^{3+}$ site in ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{VO}}_{4}$ shifts these transitions to higher temperatures in T phase ($x=0.0$ and 0.10). At $x=0.175$ [in (T $+$ M) phase], these transitions become closer to each other. Beyond this concentration, a single broad antriferromagnetic transition is observed in M $(x=0.20\ensuremath{-}0.30$) and O ($x=0.90\ensuremath{-}1.0$) phases. A nonlinear behavior in isotherm M-H curves below ${\mathrm{T}}_{N2}$ indicates field-induced spin-reorientation transitions at higher magnetic field. In dielectric permittivity $\ensuremath{\varepsilon}$ a sharp peak at ${\mathrm{T}}_{N2}$ in T and near M regions with a minimal suppression because of applied magnetic field is found and no such peak is observed in far M phase. A discontinuity evidenced in electromagnetic susceptibility indicates magnetoelectric effect at the polar to nonpolar transition regions. The structural incongruence in progressive transformation from T to M to O symmetries plays a vital role in controlling the nature of magnetic interactions. Our results indicate a strong correlation between structural transitions, magnetolattice coupling, magnetic frustrations, and magnetoelectric effect in ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{VO}}_{4}$.

Electric-field control of spin orientation of manganocene: An insight into molecule-substrate interactions.

The manipulation of spin orientations in molecular nanomagnets assembled on surfaces is essential for the development of memory devices. These properties are dominated by interactions with the substrate. Here, we show that individual manganocene molecules deposited on Cu(111) exhibit different easy magnetization directions in an applied electric-field due to different contact geometries. Using Hubbard-U corrected density-functional theory to describe strong correlation effects and a non-self-consistent diagonalization method to treat spin-orbit coupling, we demonstrate that the field-induced spin reorientation transition occurs in the standing-up molecule in both high-spin (HS) and low-spin states, while the transition only occurs in the HS state for the flat-lying molecule. We propose plausible mechanisms in terms of charge polarization at the interface as well as modifications of the electronic states near the Fermi level E F. We show that the molecule largely preserves its arrangement of 3d orbitals in the standing configuration due to the "insulating layer" (bridging ligand), whereas direct contact of the Mn ion with the substrate in the lying configuration induces an orbital degeneracy around E F, thus preventing the electrical modulation of magnetic anisotropies.

Study of orthorhombic twins in epitaxial GdFeO3 thin films

Thin films of GdFeO3 (GdFO) have been grown on two (00l) oriented single crystal substrates viz., LaAlO3 and SrTiO3 using pulsed laser ablation method. Phase purity of the prepared samples is confirmed from x-ray 2θ − ω measurements. From the x-ray phi-scans and reciprocal space mapping measurements, it is observed that GdFO films are epitaxial and grow in (00l) out-of-plane orientation. It is observed that the GdFO grows along the diagonal of the substrate cube with in-plane 90o rotated orthorhombic twins for both the substrates. Magnetization data shows the signatures of Gd3+ ordering and magnetic field induced spin re-orientation similar to that of bulk GdFO for both the substrates. However, surface morphology is found to be different for both the substrates resulting in considerable changes of O K-edge near absorption spectra.

Temperature and field induced spin reorientation and dielectric properties in YCr0.88Fe0.12O3 single crystal

The structural, magnetic, and dielectric properties of the YCr0.88Fe0.12O3 single crystals were studied. Detailed magnetic studies demonstrate that the crystal is antiferromagnetic with weak canted ferromagnetism and experiences three sequential magnetic transitions around TN1 ∼ 127.3 K, TN2 ∼ 115.2 K, and TSR ∼ 99.0 K. Interestingly, a temperature induced spin reorientation (SR) near TSR and magnetic field induced SR below TSR were observed. The H–T phase diagram was revealed to be quite different from both parent compounds YFeO3 and YCrO3. A dielectric relaxation around TN1 was found to be associated with electron hopping. An intrinsic magnetoelectric effect was also observed at low temperatures. These results are helpful for understanding the exotic magnetic and magnetoelectric properties in the orthochromite and orthoferrite related systems.

Equiatomic compounds REIrMg (RE = Y, La-Nd, Sm, Gd-Tm) and RERhMg (RE = Y, Sm, Gd-Tm)

The equiatomic intermetallic compounds REIrMg (RE = Y, La-Nd, Sm, Gd-Tm) and RERhMg (RE = Y, Sm, Gd-Tm) were synthesized from the elements in sealed niobium ampoules in a high-frequency furnace and characterized based on X-ray powder data. LaIrMg and CeIrMg crystallize with the orthorhombic LaNiAl type structure (Pnma), while all other compounds adopt the TiNiSi type. The structures of YRhMg, GdRh1.190(4)Mg0.810(4), DyRh1.126(5)Mg0.874(5), LaIrMg, NdIr1.033(2)Mg0.967(2) and ErIr1.059(3)Mg0.941(3) were refined from single-crystal X-ray diffractometer data. The striking structural motifs of these phases are tricapped trigonal prisms around the transition metal atoms formed by RE and Mg. The two structure types differ in the connectivity pattern of the trigonal prisms. The rhodium (iridium) atoms build up three-dimensional [RhMg] and [IrMg] networks in which cavities are filled by the rare earth atoms. Temperature dependent magnetic susceptibility measurements on X-ray pure samples of NdIrMg, SmRhMg, GdRhMg, TbRhMg and DyRhMg show Curie-Weiss paramagnetism of the trivalent rare earth ions and magnetic ordering at low temperatures: TC = 9.5K for NdIrMg and Néel temperatures of 10.0, 16.7, 10.6 and 11.3K for SmRhMg, GdRhMg, TbRhMg and DyRhMg. TbRhMg and DyRhMg exhibit field-induced spin reorientations (metamagnetism).

Study of spin-phonon coupling and magnetic field induced spin reorientation in polycrystalline multiferroic [formula omitted

The present work reports the preparation of polycrystalline multiferroic GdFeO3 (GdFO) and characterization with x-ray diffraction (XRD), magnetization, temperature dependent Raman spectroscopy, temperature and magnetic field dependent F57e Mössbauer spectroscopy measurements. The sample is found to be phase pure from Rietveld refinement of XRD pattern. The Mössbauer spectra measured in the presence of external magnetic field show the signatures of field induced spin reorientation transition, which are corroborated by magnetization measurements. From the temperature dependent variation of internal hyperfine field, Neel transition temperature (TN,Fe) of 672.5 ± 0.2 K and critical exponent (β) of 0.333 ± 0.003 is obtained. Temperature dependent (300–760 K) Raman spectroscopy measurements show the signatures of spin-phonon coupling and local structural re-arrangement across TN,Fe.

Temperature and Magnetic Field-Induced Spin Reorientation in Rare-Earth Perovskite ErFe0.75Cr0.25O3

We report the synthesis of a single-phase rare-earth perovskite ErFe0.75Cr0.25O3 polycrystalline and its magnetic properties. A transition occurs at temperature T N = 120 K below which we observe a weak magnetic moment from the canted antiferromagnetism. Interestingly, ErFe0.75Cr0.25O3 reveals the compensation-like behavior at T comp−like = 27 K, where the net magnetic moments of transition-metal ions are antiparallel and equal to the induced net moment of Er3+ ions, and the paramagnetic contribution of Er3+ moment presenting a nonzero magnetization. The temperature-dependent magnetization measurement shows a spin reorientation transition from Γ4 to Γ1 at 6 K. Furthermore, it is also observed that there is a spin-flop transition at low temperature induced by external magnetic field in Γ1 state (antiferromagnetic state). The interaction between (Fe/Cr)-3d and Er-4f electrons drives an extremely interesting spin reorientation transition which is highly sensitive to magnetic field and temperature.