Bi-flux Method Research Articles

La2RhSb4: a new ternary superconducting rhodium-antimonide

Rhodium-containing compounds offer a fertile playground to explore novel materials with superconductivity (SC) and other fantastic electronic correlation effects. A new ternary rhodium-antimonide La2RhSb4 () has been synthesized by a Bi-flux method. It crystallizes in the orthorhombic Pr2Ir3Sb4-like structure, with the space group Pnma (No. 62). The crystalline structure appears as stacking the two-dimensional RhSb4- and RhSb5-polyhedra networks along b axis, and the La atoms embed in the cavities of these networks. Band structure calculations confirm it as a multi-band metal with a van-Hove singularity like feature at the Fermi level, whose density of states are mainly of Rh-4d and Sb-5p characters. The calculations also imply that the redundant Rh acts as charge dopant. SC is observed in this material with onset transition at K. Ultra-low temperature magnetic susceptibility and specific heat measurements suggest that it is an s-wave type-II superconductor. Our work may also imply that the broad Sb4 (Ln = rare earth, Tm = Rh, Ir) family may host new material bases where new superconductors, quantum magnetism and other electronic correlation effects could be found.

Antiferromagnetic order in Yb4Ru7As6 with the cubic U4Re7Si6-type structure

We investigated the electronic properties of Yb4Ru7As6 using single crystalline samples grown by the Bi-flux method. Yb4Ru7As6 crystallizes in the cubic U4Re7Si6-type structure. From the electrical resistivity, magnetic susceptibility, and specific heat measurements, we have found that Yb4Ru7As6 orders antiferromagnetically below the Néel temperature of 2.5 K with the moderately enhanced electronic specific heat coefficient of 120 mJ/(Yb-mol⋅K2). A rapid increment in magnetization of about 0.25 μB/Yb has been detected at low magnetic field below 4 K, implying a weak ferromagnetic component.

Crystal growth and magnetic properties of LaMn0.91Sb2 and NdMn0.88Sb2

In this work, single crystals of ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ with deficiencies of Mn have been successively grown by using the Bi-flux method. They all crystallize in the ${\mathrm{HfCuSi}}_{2}$-type tetragonal structure with space group $P4$/nmm (No.129). ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ displays signs of successive antiferromagnetic transitions around 133 and 108 K for $H||c$. In the case of $H\ensuremath{\perp}c$, ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ shows signs of weak ferromagnetic transition around 138 K and antiferromagnetic transition at 56 K. However, there is no anomaly observed in the temperature-dependent specific heat curve. For ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ measured with $H||c$, the Mn sublattice orders antiferromagnetically below 170 K and the Nd sublattice shows successive antiferromagnetic orders at 34 and 26 K. The antiferromagnetic state of Nd sublattice can be induced to be a ferromagnetic state through a spin-flop transition at 2 K. When $H\ensuremath{\perp}\mathrm{c}$, the Mn sublattice displays antiferromagnetic orders at 171, 156, and 74 K. The Nd sublattice orders antiferromagnetically below 32 K. Ferromagnetic state for the Nd sublattice is induced by magnetic fields through a spin-flop transition at 2 K. Magnetic phase diagrams for ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ are depicted for cases of $H||c$ and $H\ensuremath{\perp}c$, respectively. ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ show metallic behavior. Negative magnetoresistance in ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ are possibly related to canted-antiferromagnetic orders of Mn sublattices.

Anisotropic magnetoresistance and possible weak antilocalization in Mg3Bi2 single crystal

Kagome compound Mg3Bi2 has recently been proposed as a type-II nodal-line semimetal, which may exhibit novel transport phenomena. We grew Mg3Bi2 single crystals by a Bi flux method and systematically investigated the magneto-transport properties. A large transverse magnetoresistance anisotropy around 20 was observed for I // (00l) at 2 K under a magnetic field of 5 T. The gourd-shaped out-plane angle-dependent magnetoresistance indicates that the Fermi surface has a two-fold symmetry and strong anisotropy. The cusp-like magnetoresistance for I // (0kl) (k = integer, ) at low temperature and low magnetic field shows evidence of weak antilocalization. The magnetoconductance measured at different angle merges together when plotted as a function of at , showing that the domination of topological surface states when .

Electrical performance enhancement by resonant states in PbSe single-crystal growth via Bi-flux method

Electrical performance enhancement by resonant states in PbSe single-crystal growth via Bi-flux method

Single crystal growth of GaSe via bismuth flux method and its air-stability

Gallium selenide (GaSe) shows potential applications in photoelectric fields. Herein, we successfully synthesized GaSe single crystal with large size via improved Bi-flux method. X-ray diffraction pattern and energy dispersive spectrum show the high crystallinity and high homogeneity of GaSe crystal. Optical absorption and photoluminescence measurements illustrate the band gap of the crystal is ~ 2 eV. Photocurrent behavior demonstrates the photoelectric response time is determined to be 2.08 s. The time dependent Raman spectrum shows that GaSe grown by Bi-flux method degenerates slowly under continuous air-exposure. This effective new growth method would be helpful for photoelectric device and two-dimensional materials study based on GaSe.

Crystal structure and physical properties of AePd1-xP1+x (Ae = Ca, Sr)

We report the discovery of two new compounds AePd1-xP1+x (Ae = Ca, Sr) crystallized in different hexagonal structures. Single crystals of AePd1-xP1+x (Ae = Ca, Sr) are obtained using the Bi-flux method. Crystallographic analysis by both powder and single crystal X-ray diffraction shows that CaPd1-xP1+x crystallizes in a non-centrosymmetric hexagonal structure with the space group P-6m2 (No.187) and lattice parameters a = b = 4.0391(9) Å and c = 4.1026(9) Å, while SrPd1-xP1+x forms a centrosymmetric hexagonal structure with the space group P63/mmc (No. 194) and lattice parameters a = b = 4.102(2) Å and c = 8.713(4) Å. In both compounds, Pd and P atoms mix in the honeycomb layer with a higher amount of P. The electronic structure calculations show that the mixture of Pd and P atoms in the honeycomb network is critical to stabilize the crystal structures. AePd1-xP1+x (Ae = Ca, Sr) are diamagnetic metals confirmed by the magnetic susceptibility, electrical resistivity and specific heat.

Effect of hole modulation on the electrical transport properties and thermal stability of single crystal α-Cu2Se prepared by Bi-flux method

In this study, α-Cu2Se single crystal with space group C2/c was prepared by the Bi-flux method according to the stoichiometric ratio of Cu2Se(1+x)Bi3 (x = 0, 0.01, 0.02, 0.03). All samples involve hole conduction and carrier concentration increases with the increase of Se content. The valence of Bi atom is +3 in the sample, and the solubility limit of Bi atom is approximately 0.012% in Cu2Se. The crystal cell volume of all samples is larger than that of standard α-Cu2Se for the larger ion radius of Bi3+ than Cu+. In addition, the crystal cell volume of the samples decreases with the increase of Se content because of more Cu vacancies caused by excessive Se. The transmission electron microscopy image and the corresponding area electron diffraction pattern show that the prepared samples have a complete crystal structure. Eventually, the single crystal α-Cu2Se1.01 sample obtains the highest power factor of 1.53 × 10−3 W m−1 K−2 at 690 K. Thermogravimetric-differential thermal analysis shows that no weight loss occurred below the melting point. After three continuous thermal cycles, the value of power factor drops down to ∼0.04 × 10−3 W m−1 K−2 at 660 K. In comparison with polycrystalline sample prepared by hot pressing, the thermal stability is improved obviously.

Structural and magnetotransport properties of topological trivial LuNiBi single crystals

In this work, we have grown the high-quality LuNiBi single crystals by a Bi flux method. The band gaps from calculation and fitting RT curve both show a small value that indicates LuNiBi is a gapless semiconductor. And we present the magnetic field dependency of transport properties for LuNiBi single crystal. Because of the strong spin-orbital coupling (SOC), some fascinating transport properties were observed. A cusp in the low magnetic field region that is similar to weak antilocalization (WAL) effect was observed in magnetoresistance (MR). And large MR reaching to 105% at a field of 2T and 81% at 1T field makes LuNiBi single crystal become a potential material candidate for applications in high-sensitivity magnetic sensors.

Magnetic and magnetotransport properties of single-crystalline R2PdGe6 (R = Pr, Gd and Tb)

Single crystals of R2PdGe6 (R = Pr, Gd and Tb) compounds were grown by the Bi-flux method. Pr2PdGe6 is an antiferromagnetic compound with Néel temperature TN = 15 K, in which a field-induced magnetic transition (spin flip) occurs when a magnetic field is applied along either a or b axis; a small magnetization and hysteresis loop were observed when a field is applied along c axis. Gd2PdGe6 is a collinear antiferromagnetic compound with TN = 37 K along b axis. Tb2PdGe6 is an antiferromagnetic compound with TN = 48 K and its hard magnetization direction is along b axis. The temperature dependences of the resistance of the entire three compounds present inflection points at the respective TN. A large resistance (as well as magnetoresistance) change can be found at the spin flip transition of Pr2PdGe6, but the change is not obvious at the spin flop transition of Gd2PdGe6.

Superlattice formation lifting degeneracy protected by nonsymmorphic symmetry through a metal-insulator transition in RuAs

The single crystal of RuAs obtained by Bi-flux method shows obvious successive metal-insulator transitions at T_MI1~255 K and T_MI2~195$ K. The X-ray diffraction measurement reveals a formation of superlattice of 3x3x3 of the original unit cell below T_MI2, accompanied by a change of the crystal system from the orthorhombic structure to the monoclinic one. Simple dimerization of the Ru ions is nor seen in the ground state. The multiple As sites observed in nuclear quadrupole resonance (NQR) spectrum also demonstrate the formation of the superlattice in the ground state, which is clarified to be nonmagnetic. The divergence in 1/T_1 at T_MI1 shows that a symmetry lowering by the metal-insulator transition is accompanied by strong critical fluctuations of some degrees of freedom. Using the structural parameters in the insulating state, the first principle calculation reproduces successfully the reasonable size of nuclear quadrupole frequencies for the multiple As sites, ensuring the high validity of the structural parameters. The calculation also gives a remarkable suppression in the density of states (DOS) near the Fermi level, although the gap opening is insufficient. A coupled modulation of the calculated Ru d electron numbers and the crystal structure proposes a formation of charge density wave (CDW) in RuAs. Some lacking factors remain, but it shows that a lifting of degeneracy protected by the non-symmorphic symmetry through the superlattice formation is a key ingredient for the metal-insulator transition in RuAs.

Observation of weak antilocalization effect in high-quality ScNiBi single crystal

In this paper, we have successfully grown the high-quality ScNiBi single crystals by a Bi flux method and investigated their electronic-transport properties. It was found that the ScNiBi single crystal is a gapless semiconductor with positive linear magnetoresistance (MR). Moreover, the field-dependent MR in the low-field region has demonstrated obvious weak antilocalization (WAL) effect below 50 K. The extremely large prefactor α and angle-dependent magnetoconductance ΔGxx suggest that the WAL effect originates from the contribution of a strong bulk spin-orbital coupling.

Linear magnetoresistance in a topological insulator Ru2Sn3

We have studied magnetotransport properties of a topological insulator material Ru2Sn3. Bulk single crystals of Ru2Sn3 were grown by a Bi flux method. The resistivity is semiconducting at high temperatures above 160 K, while it becomes metallic below 160 K. Nonlinear field dependence of Hall resistivity in the metallic region shows conduction of multiple carriers at low temperatures. In the high-temperature semiconducting region, magnetoresistance exhibits a conventional quadratic magnetic-field dependence. In the low-temperature metallic region, however, high-field magnetoresistance is clearly linear with magnetic fields, signaling a linear dispersion in the low-temperature electronic structure. Small changes in the magnetoresistance magnitude with respect to the magnetic field angle indicate that bulk electron carriers are responsible mainly for the observed linear magnetoresistance.

21pBM-13 Biフラックス法を用いたYbMn_6Ge_6単結晶の育成と物性

21pBM-13 Biフラックス法を用いたYbMn_6Ge_6単結晶の育成と物性

Kondo effect in the quasiskutteruditeYb3Os4Ge13

We report the crystal growth of a new compound, Yb3Os4Ge13, by using a Bi-flux method. X-ray diffraction measurement shows that it crystallizes in the quasi-skutterudite-type caged structure with a cubic space group of Pm-3n (No. 223). Magnetic measurements reveal almost fully localized Yb f-moments above 120 K. The resistivity exhibits a crossover from metallic to insulating behavior with a logarithmic increase below ~ 40 K. The specific heat coefficient shows a rapid upturn below ~5 K and exceeds 2 J mol-1 K-2 at 2 K. Our experimental analysis and electronic band structure calculations demonstrate that Yb3Os4Ge13 exhibits the Kondo effect due to strong hybridization of the localized Yb f-moments with the p-electrons of the surrounding Ge-cages.

Electron spin resonance of the half-Heusler antiferromagnet GdPdBi

We present electron spin resonance (ESR) measurements at X-Band frequency (ν=9.5GHz) in powdered single crystal of the half-Heusler antiferromagnet GdPdBi grown using a Bi-flux method. In the paramagnetic state, a single Gd3+ Dysonian ESR line is observed with a nearly temperature independent g-factor of ≈1.99(2). On the other hand, the ESR linewidth ΔH increases non-linearly with decreasing temperature, indicating that the dominant relaxation mechanism occurs via Gd3+ spin–spin interaction. Approaching the AFM transition at TN ≈13K, the Gd3+ ESR line shifts to higher fields due to the emergence of short-range AFM correlations. Complementary data from macroscopic measurements such as magnetic susceptibility, heat capacity and electrical resistivity measurements provide further details about the global macroscopic physical properties of the GdPdBi compound.

Magnetic Properties of RCoGe3(R: Ce, Pr, and Nd) and Strong Anisotropy of the Upper Critical Field in Non-centrosymmetric Compound CeCoGe3

We grew single crystals of RCoGe 3 (R: La, Ce, Pr, and Nd) by the Bi-flux method, and studied the magnetic properties of PrCoGe 3 and NdCoGe 3 and the pressure-induced superconducting property of CeCoGe 3 . These compounds crystallize in a non-centrosymmetric tetragonal structure. PrCoGe 3 and NdCoGe 3 were found to be a paramagnet and an antiferromagnet with the Neel temperature T N = 3.8 K, respectively. Crystalline electric field (CEF) schemes were proposed for PrCoGe 3 and NdCoGe 3 . The magnetic property of a pressure-induced superconductor CeCoGe 3 is highly different from those of PrCoGe 3 and NdCoGe 3 , or a similar pressure-induced superconductor CeIrSi 3 . This was discussed in connection with the superconductivity of CeCoGe 3 . We clarified the upper critical field H c2 for H ∥[001] and [100] by measuring the electrical resistivity under pressure P in magnetic fields: H c2 (0) ≃24 T for H ∥[001] and H c2 (0) ≃3.1 T for H ∥[100] at 0 K at P = 7.1 GPa. A huge H c2 (0) value for H ∥[001] is a comb...

Single crystal growth and pressure effect of an antiferromagnet [formula omitted

We succeeded in growing single crystals of an antiferromagnet Ce 2 CuGe 6 with the non-centrosymmetric orthorhombic crystal structure by the Bi-flux method. The magnetic properties were studied by measuring the magnetic susceptibility, specific heat and electrical resistivity at ambient pressure and under high pressure. The antiferromagnetic easy-axis is found to be the [0 1 0] direction ( b-axis), while the other directions correspond to hard-axes in magnetization. Furthermore we studied an effect of pressure on the electronic state by measuring the electrical resistivity under pressures up to 8 GPa. The Néel temperature T N with T N = 15.4 K at ambient pressure increases slightly with increasing pressure, and then decreases rapidly above 5 GPa. The Néel temperature is found to be zero around 7.2 GPa. The heavy fermion state is formed in this pressure region.

Thermodynamics Investigation on Pressure-induced Superconductor CeNiGe3by ac Calorimetry

We measured the heat capacity of the pressure-induced superconductor CeNiGe 3 by the ac calorimetry under high pressure up to 2.4 GPa using a single crystal sample grown by the Bi-flux method. The heat capacity C ac shows the λ-type anomaly at Neel temperature T N . The pressure dependence of T N is consistent with those determined previous studies by the resistivity measurement under high pressure. At 2.1 and 2.4 GPa, the heat capacity anomaly was observed around 0.3 K. This temperature is close to the superconducting transition temperature T sc determined by the previous resistivity measurement. Therefore, the heat capacity anomaly may be due to the superconducting transition. The value of T sc by the present heat capacity measurement was larger than those by the resistivity measurement. This might reflect a sample dependence.

Itinerant 5 f Electrons and the Fermi Surface Properties in an Enhanced Pauli Paramagnet NpGe3

We succeeded in growing a high-quality single crystal of an enhanced Pauli paramagnet, NpGe 3 , by the Bi-flux method, and observed the de Haas–van Alphen (dHvA) effect. The topology of a Fermi surface is well explained by the relativistic linear augmented-plane-wave (LAPW) band calculations based on the 5 f itinerant band model. The Fermi surface consists of a nearly spherical electron-Fermi surface with necks along the direction, forming a hollow ball, centered at the R point, which is derived from the single band. The cyclotron effective mass is in the range from 2.6 to 16 m 0 , which is enhanced approximately 3.5 times from the corresponding band mass.