Er Magnetic Moments Research Articles

The magnetic structure and spin-reorientation of ErGa.

The magnetic structure of the intermetallic compound ErGa has been determined using high-resolution neutron powder diffraction. This compound crystallizes in the orthorhombic (Cmcm, No. 63) CrB-type structure and orders ferromagnetically at 32 (2) K, with the Er moments initially aligned along the b axis. Upon cooling below 16 K, the Er magnetic moments cant away from the b axis towards the c axis. At 3 K, the Er moment is 8.7 (3) μB and the Er magnetic moments point in the direction 31 (3)° away from the crystallographic b axis, within the bc plane. 166Er Mössbauer spectroscopy work supports this structure and shows clear signals of the spin-reorientation in both the magnetic and electric quadrupole hyperfine interactions.

New insight into tuning magnetic phases of RMn6Sn6 kagome metals

Predicting magnetic ordering in kagome compounds offers the possibility of harnessing topological or flat-band physical properties through tuning of the magnetism. Here, we examine the magnetic interactions and phases of ErMn6Sn6 which belongs to a family of RMn6Sn6, R = Sc, Y, Gd–Lu, compounds with magnetic kagome Mn layers, triangular R layers, and signatures of topological properties. Using results from single-crystal neutron diffraction and mean-field analysis, we find that ErMn6Sn6 sits close to the critical boundary separating the spiral-magnetic and ferrimagnetic ordered states typical for non-magnetic versus magnetic R layers, respectively. Finding interlayer magnetic interactions and easy-plane Mn magnetic anisotropy consistent with other members of the family, we predict the existence of a number of temperature and field dependent collinear, noncollinear, and noncoplanar magnetic phases. We show that thermal fluctuations of the Er magnetic moment, which act to weaken the Mn-Er interlayer magnetic interaction and quench the Er magnetic anisotropy, dictate magnetic phase stability. Our results provide a starting point and outline a multitude of possibilities for studying the behavior of Dirac fermions in RMn6Sn6 compounds with control of the Mn spin orientation and real-space spin chirality.

Symmetry analysis of complex magnetic structure in monoclinically distorted Er3Cu4Sn4.

The magnetic structure in Er3Cu4Sn4 has been determined using high-resolution powder neutron diffraction, supported by symmetry analysis. At low temperatures, Er3Cu4Sn4 assumes a crystal structure of the Tm3Cu4Sn4 type (in the monoclinic space group C2/m). The Er atoms occupy two distinct Wyckoff sites: 2c and 4i. It has been found that the Er magnetic moments on the 2c site form a commensurate antiferromagnetic structure (k1 = [0, 0, ½]) below 6 K. The magnetic moments reach 8.91 (8) μB at 1.4 K and are parallel to the b axis. The Er magnetic moments on the 4i site order below 2 K and form an incommensurate antiferromagnetic sine-modulated structure (k2 = [1, 0.4667 (1), ½]), with magnetic moments lying in the ac plane and perpendicular to the a axis. The amplitude of modulation equals 8.7 (1) μB at 1.4 K.

High-resolution optical spectroscopy and modeling of spectral and magnetic properties of multiferroic ErFe3(BO3)4

We carried out the high-resolution broadband temperature-dependent polarized optical spectroscopy and theoretical studies of $\mathrm{ErF}{\mathrm{e}}_{3}{(\mathrm{B}{\mathrm{O}}_{3})}_{4}$ single crystals in the paramagnetic and antiferromagnetic $(Tl{T}_{N}=39\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ phases. On the basis of the experimentally determined 45 crystal-field (CF) levels of $\mathrm{E}{{\mathrm{r}}^{3}}^{+}$ ions at sites with the ${C}_{2}$ point symmetry, CF calculations were performed, a set of physically grounded CF parameters was obtained and used to model the temperature dependences of the Er magnetic moments measured in neutron-scattering experiments, as well as the magnetic susceptibility and magnetization of the compound; the contributions of the quasi-one-dimensional iron magnetic subsystem were calculated in the frame of the previously developed self-consistent four-particle cluster model. The modeling strongly supports an easy-plane collinear structure of iron magnetic moments and excludes earlier proposed additional magnetic phase.

Irradiation-induced amorphized state of rapidly quenched R 12Fe82B6 alloys (R = Nd, Er)

Rapidly quenched (RQ) alloys R12Fe82B6 (R = Nd, Er) have been prepared by melt spinning. Their magnetic properties, structure, and phase composition have been studied before and after fast-neutron irradiation to a fluence of 1.2 × 1020 n/cm2. Before irradiation, it is the Nd2Fe14B-type phase (space group P42/mnm) that is mainly present in the RQ alloys at 295 K. In the Nd12Fe82B6 alloy, this phase has a ferro-magnetic structure with magnetic moments at the Nd and Fe atoms oriented parallel to the c axis; the Er2Fe14B phase found in the Er12Fe82B6 alloy is characterized by a ferrimagnetic order of Er and Fe magnetic moments parallel to the basal plane. After irradiation, the crystalline state of both RQ alloys transforms into an amorphous state. The ferro- and ferrimagnetic orders are retained in them, but the Curie temperature of the alloys with Nd and Er decreases by 100 and 200 K, respectively. The spontaneous magnetization of the irradiated alloys at 5 K is approximately equal to their magnetization in the crystalline state, whereas their coercive force is lower than that for the alloys before irradiation by two orders of magnitude. The effects observed are explained by the dispersion of Fe-Fe exchange interactions resulting from the dispersion of interatomic spacings in the amorphous alloys.

Effects of high pressure on the magnetism of ErCo2

This paper presents the results of a high pressure study on the ferrimagnetic compound ErCo2, which exhibits at ambient pressure magnetic ordering below TC = 33 K, where the localized Er magnetic moments order ferromagnetically, and the itinerant moments in the Co sublattice, align antiparallel to the Er moments. In the paramagnetic range, clustering of the Co moments is observed below Tf ∼ 100 K for which the term “parimagnetism” has been proposed. In contrast to the pronounced peak in the AC susceptibility data at TC only a tiny “bump” shows up at Tf. The decrease of both TC and Tf with applied hydrostatic pressure has been observed, the first one being in agreement with previously published data. At higher pressures, an asymmetry in the TC-related AC susceptibility peak has been observed owing to a decoupling of the magnetic ordering phenomena in the Er and Co sublattices. Compared to earlier published results, our magnetization measurements at higher pressures above PC reveal a small but clearly observable evolution of both the critical temperature and saturated magnetization.

Crystal and magnetic properties of Er 5Ni 2In 4 at low temperatures

The Er 5Ni 2In 4 compound belongs to a novel family of rare earth-based intermetallics crystallizing within the Lu 5Ni 2In 4-type structure ( Pbam Space group). In this paper we report results of structural as well as magnetic studies including X-ray diffraction (between 12 and 300 K); neutron diffraction (between 1.5 and 24 K), magnetometric and calorimetric data (in 2–300 K temperature range). The Er 3+ ions occupy three crystal positions within the unit cell: two 4g sites and the 2a site. According to results of neutron diffraction, the Er magnetic moments at 4g sites form a non-collinear magnetic structure below 18.5 K. Additional magnetic transition at about 2 K, originating in ordering of the 2a sublattice, occurs as well. In addition, magnetic entropy derived on the basis of specific heat studies is discussed yielding the doublet crystal field ground states for each of the sublattices.

Neutron diffraction studies of RSn 1+ xGe 1− x ( R=Tb–Er) compounds

The magnetic structures of RSn 1+ x Ge 1− x ( R=Tb, Dy, Ho and Er, x≈0.1) compounds have been determined by neutron diffraction studies on polycrystalline samples. The data recorded in a paramagnetic state confirmed the orthorhombic crystal structure described by the space group Cmcm. These compounds are antiferromagnets at low temperatures. The magnetic ordering in TbSn 1.12Ge 0.88 is sine-modulated described by the propagation vector k=(0.4257(2), 0, 0.5880(3)). Tb magnetic moment equals 9.0(1) μ B at 1.62 K. It lies in the b–c plane and form an angle θ=17.4(2)° with the c-axis. This structure is stable up to the Nèel temperature equal to 31 K. The magnetic structures of RSn 1+ x Ge 1− x , where R are Dy, Ho and Er at low temperatures are described by the propagation vector k=(1/2, 1/2, 0) with the sequence (++−+) of magnetic moments in the crystal unit cell. In DySn 1.09Ge 0.91 and HoSn 1.1Ge 0.9 magnetic moments equal 7.25(15) and 8.60(6) μ B at 1.55 K, respectively. The moments are parallel to the c-axis. For Ho-compound this ordering is stable up to T N=10.7 K. For ErSn 1.08Ge 0.92, the Er magnetic moment equals 7.76(7) μ B at T=1.5 K and it is parallel to the b-axis. At T t=3.5 K it tunes into the modulated structure described by the k=(0.496(1), 0.446(4), 0). With the increase of temperature there is a slow decrease of k x component and a quick decrease of k y component. The Er magnetic moment is parallel to the b-axis up to 3.9 K while at 4 K and above it lies in the b–c plane and form an angle 48(3)° with the c-axis. In compounds with R=Tb, Ho and Er the magnetostriction effect at the Nèel temperature is observed.

Field-induced ferromagnetic structure inEr2Ni2Pb

We have studied the effect of magnetic fields up to 4.5 T on the ground-state structure inEr2Ni2Pb using powder neutron diffraction measurements at low temperatures. The zero-field magneticstate that itself is not uniform and consists of different magnetic phases is rather unstableagainst the magnetic field. As the field is increased, the magnetic reflections of the zero-fieldstructure disappear and a new magnetic phase with commensurate propagation vector isclearly observed in a field of 0.5 T. At higher fields a ferromagnetic state is established inEr2Ni2Pb, which can be fully described only by a model that combines at least twoirreducible representations. The refined Er magnetic moment magnitude of9.10 ± 0.07 µB is very closeto the Er3+ freeion value of 9.0 µB.

Magnetic structure of Er6Ni2Sn

Abstract The crystallographic and magnetic structures of Er 6 Ni 2 Sn have been determined at low temperatures using neutron powder diffraction. It has been found that this system orders antiferromagnetically (AF) below T N = 17 K. Data taken at low temperatures and analyzed using symmetry group analysis suggest that Er 6 Ni 2 Sn forms a complex non-collinear commensurate AF structure with strongly reduced Er magnetic moments. The reason for the reduced moments is unclear and needs further studies. The magnetic phases below 7 K and in the temperature range 7–17 K differ only in the Er magnetic moment magnitudes and in the angle that the Er moments at the 8 l site make with the c -axis. The extra reflections present in the powder diffraction patterns suggest presence of a secondary phase. The temperature evolution of the powder pattern indicates that the secondary phase orders AF at 35 K.

Ferrimagnetic correlations in paramagnetic [formula omitted

We have performed X-ray magnetic circular dichroism experiments on ErCo 2 in order to measure the Er and Co net magnetic moments above and below its ferrimagnetic transition. The results demonstrate the occurrence of an unexpected antiparallel alignment of Co and Er sublattices almost 30 K above the magnetic transition. We attribute this antiparallel alignment to magnetic short-range order. We have characterized the temperature dependence of the magnetic correlation length ( ξ ) with small angle neutron scattering measurements. We observe the expected divergence of ξ right above T c and, a wide region well within the paramagnetic phase, where the correlation length has an almost constant value of 7 Å . We have further observed a direct correlation between Co magnetic moment and ξ : at the onset of the long range order both magnitudes experience an abrupt increase, while the temperature range at which ξ has a constant value coincides with the change of sign of the Co magnetic moment.

Magnetic instabilities in [formula omitted] studied by NMR

The field dependence of 59Co NMR in ferrimagnetic Er 1 - x Y x Co 3 was measured up to 8 T at 4.2 K. For pure ErCo 3 in fields perpendicular to the c axis the resonance frequencies change discontinuously between 2 and 3 T due to a field induced metamagnetic transition. The transition is characterized by rotations of Er and Co magnetic moments away from the easy c-axis. The angles between the Co moments and the c axis at x = 0.1 are obtained. The easy axis is found to be along the c axis for x = 0 and 0.1, and inclined from the c axis for x = 0.3 and 0.5.

Field induced metamagnetic transition of ErCo 3 studied by NMR

Magnetic field dependence of Co 59 NMR resonance frequencies in ferrimagnetic ErCo 3 was measured in fields parallel and perpendicular to the c-axis of the crystal up to 8 T at 4.2 K. The zero field powder spectrum at 4.2 K shows three resolved lines at 23, 65, and 96 MHz, which correspond to 3b, 6c, 18h sites of Co, respectively. When field is applied along the c-axis, the resonance frequencies of 96 MHz line increase at about 10.01 MHz/T with increasing field, while those of 23 and 75 MHz lines decrease at the same rate. This means that the hyperfine field H hf is negative only for the Co 18h site, whereas at 3b- and 6c-Co it is positive. The positive H hf is resulted from a large contribution of unquenched 3d orbital moments. When field is applied perpendicular to the c-axis, the frequencies of all three resonance lines increase with increasing field, which means that H hf is negative at all the three Co sites. The resonance frequencies abruptly change around the field between 2 and 3 T due to the field induced metamagnetic transitions caused by the rotations of Er and Co magnetic moments towards the direction of the applied field from the c-axis.

Ferromagnetic ordering in ErPtIn

The magnetic ordering in ErPtIn, crystallizing in the hexagonal ZrNiAl-type structure, has been investigated by neutron diffractometry in the temperature range between 1.6 and 30.3 K. Er magnetic moment in ErPtIn has been found to order ferromagnetically below 13(1) K. The erbium magnetic moment is parallel to the c-axis. Bulk magnetic measurements are also reported.

Magnetic structure of Er5Si4

As part of our ongoing study of giant magnetocaloric compounds, we have determined the magnetic structure of Er5Si4 by high-resolution neutron powder diffraction, ac-susceptibility, and Er166 Mössbauer spectroscopy. The crystal space group is orthorhombic Pnma and the magnetic space group is Pn′ma′. The magnetic ordering temperature is 32(3) K and the magnetic structure is characterized by ferromagnetic order of the three Er sites (4c, 8d1, and 8d2) along [010], together with antiferromagnetic order of the 8d sites in the perpendicular (010) plane. The Er 4c magnetic mode is FY and the 8d magnetic mode is CX+FY+GZ+. At 3.6 K, the Er magnetic moments are 7.4(1), 6.9(2), and 7.6(2) μB at the 4c, 8d1, and 8d2 sites, respectively, and the corresponding Er166 hyperfine magnetic fields, at 5 K, are 715(5), 627(2), and 736(3) T. The neutron diffraction data show tentative evidence of a reorientation of the magnetic structure, most likely involving the development of an antiferromagnetic component at the 4c site, between 14 and 4 K.

Weak ferromagnetic order in the superconductingErNi211B2C

${\mathrm{ErNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ is the first material in which a microscopic coexistence between weak ferromagnetism (WFM) and superconductivity (SC) was confirmed by neutron diffraction technique. In the present paper, we report the detailed WFM structure and its ordering process. In the WFM phase, weak but clear peaks appear at $(n/2000)$ with $n=\mathrm{even}.$ The detailed analysis revealed that one from 20 Er magnetic moments contributes to the WFM ordering and such spins form ferromagnetic sheets that appear with a periodicity of $10a(\ensuremath{\sim}35\mathrm{\AA{}}).$

Magnetic phase transitions in ErRhSi

Polycrystalline sample of the ErRhSi compound have been prepared and studied by powder neutron diffraction, specific heat and electrical resistivity measurements. This compound crystallizes in the orthorhombic TiNiSi-type structure. The magnetic phase transition at T t=2.3 K and the Néel temperature T N=8.5 K have been determined by the temperature dependencies of the intensities of the magnetic peaks, specific heat and electrical resistivity. At 1.5 K a commensurate magnetic structure, described by the propagation vector k = (0 1 2 0) coexists with the incommensurate one with k =(0,0.4184(4),0) . Above T t only incommensurate phase with the propagation vector k =(0,0.4173(2),0) at 4 K exist. Er magnetic moment is parallel to the a-axis for both phases below T t and form angle ±19° with a-axis in the temperature range T t and T N.

Study of amorphous ferrimagnet Fe0.66Er0.19B0.15 by means of monochromatic circularly polarised source

Properties of amorphous alloy Fe0.66Er0.19B0.15 are reported. A reorientation of the Fe and Er magnetic moments during sample cooling through the compensation point in a large magnetic field is found by means of monochromatic circularly polarised radiation.

Magnetic properties and magnetic structures of RPtGe 2 and RIrGe 2 ( R=Gd–Er) compounds

Magnetic properties and magnetic structures of RTGe 2 ( R=Gd–Er, T=Pt, Ir) series of ternary intermetallic compounds were determined by X-ray and neutron diffraction and by magnetometric methods. All these compounds exhibit the orthorhombic YIrGe 2-type crystal structure and except ErIrGe 2, are antiferromagnetic at low temperatures. The rare earth atoms occupy the 4(i) and 4(h) sites. In the case of TbPtGe 2, TbIrGe 2 and HoIrGe 2 only the magnetic moments at the 4(i) site order below the Néel temperature (with the simple propagation vector k=0). At low temperatures the Tb and Ho moments at the 4(h) site order with different propagation vectors. In the DyPtGe 2 compound, the Dy magnetic moments at both crystallographic sites order in a collinear antiferromagnetic structure below the Néel temperatures. For ErPtGe 2 in the temperature range between 1.5 K and T N=2.8 K, only the Er magnetic moments at the 4(i) site are ordered.

Magnetic structure study of ErCuAl and ErNiAl

Polycrystalline samples of ErCuAl and ErNiAl have been studied by powder neutron diffraction and, in the case of ErCuAl, by specific heat and AC-susceptibility measurements. ErCuAl orders ferromagnetically with Er magnetic moments aligned along the c-axis below T c = 6.8 K. In the case of ErNiAl, magnetic ordering below T N = 5.4 K and indications of an additional phase transition at 4.2 K have been observed. The magnetic structure of ErNiAl is described by the propagation vector ( 1 2 , 0, 1 2 ). The magnetic moments lie in the basal plane at 1.8 K.