Anisotropic Gap in Quasiparticle Excitations in the Kondo-Lattice System

近藤晶格系统中准粒子激发的各向异性能隙

• 批准号: 08404023
• 负责人: TAKABATAKE Toshiro
• 金额: $ 26.11万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08404023/
• 关键词: Kondo Semiconductor; Energy Gap; Hybridization; Electron Tunneling; Single Crystal; Low-Carrier Density System; 強磁場; 高圧; 磁気抵抗; メタ磁性; 光電子分光; 低温高圧; 凝ギャップ; 電気抵抗; 極低温比熱

We have studied the gap formation in the Kondo-lattice systems YbB12, Ce3Bi4Pt3, CeNiSn and CeRhSb by means of high-quality single crystals. New findings are as followings.1. Anisotropic Gap : Tunnel spectroscopy revealed the B SC-type gap in YbBI2 and Ce3Bi4Pt3. Substitution of Lu for Yb in YbB12 gives rise to a midgap state with keeping the gap width unchanged. By contrast, the gap in CeNiSn and CeRhSb is anisotropic with a residual density of states. Only 1% substitution in CeNiSn leads to a unitarity scattering of the residual carriers. The gap anisotropy is much weakened in CeRhSb due to the strong hybridization.2. Ground state of CeNiSn : It is a semimetallic state with an extremely low carrier density. A sort of magnetic polaron is indicated by the anomalous field dependence of the magnetoresistance and specific heat below 0.5 K.3. Effect of high magnetic field : The gap in CeNiSn is closed by application of field of 14 TAU along the a axis. However, a higher field of 30 T is required to close the gap in CeRhSb. For YbB12, a first order transition from a semiconductor to a metal is found near 50 TAU The sharp peaks in the magnetoresistance indicate the presence of fine structure in the gap.4. Effect of pressure : CeNiSn exhibits a pressure-induced magnetism, which is the first example among the Ce-based compounds.

本文用高质量单晶研究了近藤点阵系统YbB_（12），Ce_3Bi_4Pt_3，CeNiSn和CeRhSb中的差距形成。新发现如下：1.各向异性的间隙：隧道光谱揭示了B SC型间隙在YbBI 2和Ce3Bi 4 Pt 3。用Lu取代YbB_（12）中的Yb，在保持差距宽度不变的情况下，产生了一个中间带隙态。相比之下，CeNiSn和CeRhSb中的差距是各向异性的，具有残余态密度。CeNiSn中只有1%的取代导致残余载流子的么正性散射。由于CeRhSb的强杂化作用，使其差距各向异性大大减弱. CeNiSn的基态：它是具有极低载流子密度的半金属态。在0.5K以下，磁电阻和比热的异常场依赖性表明了一种磁极化子。高磁场的影响：CeNiSn中差距通过沿着a轴施加14 TAU的磁场而闭合。然而，需要30 T的更高场来闭合CeRhSb中的差距。对于YbB12，在50 TAU附近发现了从半导体到金属的一级跃迁。磁阻的尖峰表明间隙中存在精细结构。压力效应：CeNiSn表现出压力诱导磁性，这是Ce基化合物中的第一个例子。

项目成果

M.Sera: "Anisotropic pseudogap in CeNiSn and CeRhSb studied by a thermal-conductivity measurement" Phys.Rev.B. 55. 6421-6428 (1997)

M.Sera：“通过热导率测量研究 CeNiSn 和 CeRhSb 中的各向异性赝能隙”Phys.Rev.B。

T.Ekino: "Tunneling spectroscopy of the Kondo-semiconducting gap in YbB_<12>" Physica B. (in press.). (1999)

T.Ekino：“YbB_<12> 中近藤半导体能隙的隧道光谱”Physica B.（正在出版）。

T.Takabatake: "Magnetic and structural transitions in CeRh2Sb2" Physica B. 230-232. 223-225 (1997)

T.Takabatake：“CeRh2Sb2 中的磁性和结构转变”Physica B. 230-232。

K. Kobayashi: "Anomalous scattering of quasiparticles by Co and Cu impurities in the Kondo semimetal CeNiSn" Physia B. (1997)

K. Kobayashi：“近藤半金属 CeNiSn 中 Co 和 Cu 杂质对准粒子的异常散射” Physia B. (1997)

H.Kadowaki: "Pressure effect on magnetic excitation in the Kondo Semimetal CeNiSn" Physica B. 230-232. 664-666 (1997)

H.Kadowaki：“近藤半金属 CeNiSn 中磁激励的压力效应”Physica B. 230-232。