Single crystal growth of oxycloride superconductor at high pressures and investigation of the physical properties

氯氧化物超导体的高压单晶生长及物理性能研究

• 批准号: 13440111
• 负责人: AZUMA Masaki
• 金额: $ 8.7万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440111/
• 关键词: High Temperature superconductor; Oxychloride; Single Crystal; High Pressure synthesis; Synchrotron Radiation X-ray; Photoemission; STM; μSR; アンダードープ

Because of the easy cleavage and undistorted structure, Ca_<2-x>Na_xCuO_2Cl_2 is an ideal compound for angle resolved photoemission spectroscopy (ARPES) and STM measurements. These measurements were performed on single crystal samples grown at high pressures based on the in-situ observation of the chemical reaction by means of synchrotron X-ray diffraction study.The ARPES data on x=0.1 sample (T_c=13K) were most likely described by a "chemical potential shift" which contrasts with the "pinned chemical potential" reported for La_<2-x>Sr_xCuO_4. Nano-scale patch-like and river-like irregular corrugations were observed in the STM images take for x=0.08 and 0.12 samples. The density of states changed depending on the contrast of the images, suggesting the phase separation into metallic and insulating regions.Powder samples with the overdope composition were prepared for the first time by synthesizing at even higher pressures up to 10 Gpa. μ SR studies were performed on aligned powder samples. Ca_2CuO_2Cl_2 had been known to be an antiferromagnet with T_N=250K. In Ca_<2-x>Na_xCuO_2Cl_2, T_N decreased rapidly with increasing x and disappeared at x=0.01.Single crystals of PrNiO_3 and BiMnO_3 were grown at high pressures with the technique developed in this project. Synchrotron X-ray diffractions on both single crystal and powder samples of the former revealed the presence of a structural transition accompanied by the charge disproportionation of Ni valence at the metal-insulator transition temperature. The presence of 6s^2 lone pairs in BiMnO_3 makes this compound novel ferromagnetic ferroelectric. Inspired by this compound, BiCoO_3, BiCrO_3, BiNiO_3 were investigated. All of these had distorted perovskite structures.

由于易于切割的结构，na_xcuo_2cl_2是角度分辨率y（arpes）的划分，并根据同步物在高压下生长的单晶样品对这些测量进行了测量。研究。X = 0.1上的ARPES数据很可能是通过“化学势移位”的床，与LA_ <2-X> sr_xcuo_4报道的“固定化学势”形成了鲜明的对比。 ，表明相位的分离和绝缘区域。与合成蛋白EN Highher的前剂量的抗膨胀样品最多可以在10 GPA上进行。 X> na_xcuo_2cl_2 3在此项目中开发的高压下生长。研究了Binio_3。

项目成果

M.Azuma: "Single-Crystal Growth of Transition Metal Oxides at High Pressures of Several GPa"J. Phys. : Condens. Matter. 14・44. 11111-11114 (2002)

M. Azuma：“几 GPa 高压下的过渡金属氧化物的单晶生长”J. Phys. 14・44 (2002)。

東 正樹: "GPa領域での遷移金属酸化物単結晶育成"日本物理学会誌. 57・7. 492-499 (2002)

东正树：“GPa区域的过渡金属氧化物单晶的生长”日本物理学会杂志57・7（2002年）。

M.Azuma: "Single-Crystal Growth of Transition Metal Oxides at High Pressures of Several GPa"J. Phys. : Condens. Matter. 14. 11321-11324 (2002)

M.Azuma：“过渡金属氧化物在几 GPa 高压下的单晶生长”J。

D.C.Johnston: "Modeling of the Magnetic Susceptibilities of the Ambient-and High-Pressure Phases of (VO)_2P_2O_7"Phys. Rev. B. 64. 134403-1-134403-23 (2001)

D.C.Johnston：“(VO)_2P_2O_7 环境和高压相的磁化率建模”Phys。

東 正樹: "放射光X線回折を利用した高圧合成研究"固体物理. 38. 141-150 (2003)

Masaki Higashi：“使用同步加速器辐射X射线衍射的高压合成研究”固体物理38。141-150（2003）。