Crystal growth of magnetic dihydride GdxY1−xH2 for generation of spin current

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

Sakuraba

et al. 2014

Metallic dihydride GdH 2 is known to have an antiferromagnetic phase below 20 K, whereas YH 2 is compensated paramagnetic metal in which not only carrier density but also mobility are the same between electron and hole. Since both GdH 2 and YH 2 have CaF 2 type structure, it is possible to fabricate a single phase of Gd x Y 1-x H 2 with arbitral Gd content (x). The present study is aiming at assessment of carrier effective mass of Gd x Y 1-x H 2 as a function of x. For this purpose, we have carried out (i) the optical reflectivity measurement at photon energy region including the plasma frequency and (ii) calculation of the conduction band density of states, from which carrier density can be estimated. It follows from (i) and (ii) that the reduced mass associated with the electron mass and the hole mass is estimated as a function of x, indicating the maximum value of approximately 6.3 (±0.23) m 0 at x≒0.39. Also another interpretation in terms of the carrier density and mass difference between electrons and holes will be discussed.

“…Details for (i) and (ii) are described in Ref. 8.Their crystal structures were investigated by conventional θ/2θ X-ray diffractometer (RIGAKU Ultima III) employing Cu-Kα radiation.…”

Section: Procedures Of Experiments and Analysismentioning

confidence: 99%

Section: Procedures Of Experiments and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optical Assessment of Carrier Effective Mass in Gd_xY₁₋_xH₂(0 ≦x≦ 1)

Haruyama

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

Sakuraba

et al. 2014

“…Systematic galvanomagnetic studies in the 1960s and 1970s showed that several elemental metals are CMs (i.e., Be, Mg, Zn, Cd, Ga, Tl, Sn, Pb, Bi, Sb, Mo, W, Re, Pd, and Pt) [22,23]. To date, YH 2 [24], GdH 2 [25], fcc Yb [26], and the parent states of iron pnictide and chalcogenide superconductors [27] have been found to be nearly CMs. Baber scattering accompanied by a spin flip is conceptually similar to the Bir-Aronov-Picus mechanism [28,29], which is described in terms of the electron-hole exchange interaction and plays a determining role in the spin relaxation of optically excited electrons in p-type III-V semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal characteristics of spin transport in compensated metals with electron–hole exchange interaction

J. Phys.: Condens. Matter

Aktar

Yoshizumi

et al. 2021

We develop a theory describing spatiotemporal behavior of spin transport in two-band metals by postulating a spin–exchange interaction between electrons and holes. Starting with the semiclassical Boltzmann equation, we derive a system of coupled diffusion equations and solve them analytically under steady-state conditions. The solutions reveal two types of electron–hole coupled-spin transport modes: a dissipative mode and a nondissipative mode with an infinite spin diffusion length. The two modes are the manifestations of two types of spin coupling channels. Besides the exchange interaction, we incorporate into our derivation the relaxation caused by the spin–orbit interaction to show how it affects the spin transport characteristics of the two modes.

“…In YH 2 , the level of spin polarization due to the Pauli paramagnetism is estimated to be approximately 3% at 5 T from its observed susceptibility (χ Pauli ) [3]. To enhance χ Pauli but remaining the QZHC unchanged, we have fabricated dihydride compounds of Gd-Y alloy [4], because YH 2 and GdH 2 show approximately the same characteristics in terms of crystal structure [5] and electronic structure [6,7] except the presence of 4f electrons in GdH 2 .…”

Section: Introductionmentioning

confidence: 99%

Hall Effect and Magnetoresistance in Gd_xY₁₋_xH₂(x\( \fallingdotseq \) 0.4)

Sakuraba

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

Arai

et al. 2014

We are aiming at the construction of the bipolar conducting system, the holes and electrons of which are spin-polarized such that the spin current is generated through either the ordinary or anomalous Hall effects. Taking advantage of the quasi-zero Hall coefficient characteristic (QZHC) of YH 2 in which electrons and holes have approximately the same carrier density and mobility, Gd was incorporated to form a magnetic QZHC system Gd x Y 1-x H 2 (x=0.39). The zero field specific resistivity (ρ 0), Hall resistivity (HR), and transverse magnetoresistivity (TMR) in Gd x Y 1-x H 2 (x=0.39) were measured as a function of temperature ranging from 4 to 400 K. Huge signals were observed in both HR and TMR around 210 K, well synchronized with the abrupt change observed in ρ 0. Two type of interpretation, i.e., the ordinary Hall and anomalous Hall effect models are given to discuss the feasibility of each mechanism based on our experimental results.