Studies of Symmetry of Order parameter of non-BCS superconductors by low temperature scanning tunneling microscopy and spectroscopy

非BCS超导体有序参数对称性的低温扫描隧道显微镜和光谱学研究

• 批准号: 11304021
• 负责人: NISHIDA Nobuhiko
• 金额: $ 4.27万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11304021/
• 关键词: low temperature scanning tunneling spectroscopy and microscopy; high temperature superconductors; heavy fermion superconductors; superconducting vortex lattice; Bi_2Sr_2CaCu_2O_x; YNi_2B_2C; CeRu_2; MgB_2; quasi-particle density of states; 極低温走査ト

We have developed low temperature scanning tunneling microscope (LT-STM) with which we are able to perform scanning tunneling spectroscopy (STS) with energy resolution better than 10 μeV with an atomic spatial resolution below 1K in high magnetic fields up to 12 T. At 0.45K the precise STS/STM measurements were able to be performed. Combining our developed STM probe with 3He-4He dilution refrigerator, we are now ready for STS/STM in the temperature region of 0.1K. By using thus developed STS apparatus, we have made STS studies of possible candidates of non-BCS superconductors such as Bi_2Sr_2CaCu_2O_x, YNi_2B_2C, CeRu_2, UPd_2Al_3, CeCoIn_5, Sr_2RuO_4 and MgB_2. In Bi_2Sr_2CaCu_2O_x, YNi_2B_2C, CeRu_2 we have succeeded in observing vortices. The orbital symmetries of Cooper pairing of the superconductors have been studied by LT-STS. In polycrystalline MgB_2 STS measurements were performed from grain to grain and MgB_2 have been found to be a superconductor with 2 energy gaps which can be interpreted in terms of 2-band superconductor. We have indicated that LT-STS/STM is quite a powerful method for superconductivity studies.

我们开发了一种低温扫描隧道显微镜（LT-STM），它能够在高达12 t的高磁场下进行能量分辨率优于10 μeV、原子空间分辨率低于1K的扫描隧道光谱（STS），在0.45K时能够进行精确的STS/STM测量。结合我们开发的STM探针和3He-4He稀释冰箱，我们现在可以在0.1K的温度范围内进行STS/STM。利用所研制的STS装置，对Bi_2Sr_2CaCu_2O_x、YNi_2B_2C、CeRu_2、UPd_2Al_3、CeCoIn_5、Sr_2RuO_4和MgB_2等非bcs超导体的候选材料进行了STS研究。在Bi_2Sr_2CaCu_2O_x、YNi_2B_2C、CeRu_2中，我们成功地观测到了涡旋。利用LT-STS研究了超导体库珀对的轨道对称性。在多晶MgB_2中，从晶粒到晶粒进行了STS测量，发现MgB_2是具有2个能隙的超导体，可以用2带超导体来解释。我们已经表明，LT-STS/STM是一种非常强大的超导研究方法。

项目成果

S.Kaneko, H.Sakata, Y.Ono, N.Nishida, T.Mochiku, K.Hirata: "Local electronic density of states near steps on the c-plane of Bi_2Sr_2CaCu_2Ox studied using low temperature scanning tunneling spectroscopy and microscopy"Surface Science. 438. 353-357 (1999)

S.Kaneko、H.Sakata、Y.Ono、N.Nishida、T.Mochiku、K.Hirata：“使用低温扫描隧道光谱和显微镜研究了 Bi_2Sr_2CaCu_2Ox c 平面台阶附近的局域电子密度”表面

M.Matsumoto, R.Heeb: "Vortex charging effect in a chiral px+-ipy-wave superconductors"Phys.Rev.B. 65. 014504(8) (2002)

M.Matsumoto、R.Heeb：“手性 px -ipy 波超导体中的涡流充电效应”Phys.Rev.B。

S.Kaneko, Y.Ono, N.Nishida, T.Kambara: "Columnar defect-induced strain and superconductivity in Bi_2Sr_2CaCu2Ox observed by LT-STS/STM"Surface Science. 493. 692-696 (2001)

S.Kaneko、Y.Ono、N.Nishida、T.Kambara：“通过 LT-STS/STM 观察到的 Bi_2Sr_2CaCu2Ox 中柱状缺陷引起的应变和超导性”表面科学。

H. Sakata, N. Nishida et al.: "Vortex Lattice and Quasiparticle Density of States in CeRu2 studied by Scanning Tunneling Spectroscopy"J. Phys. Soc. Jpn.. 69. 1970-1973 (2000)

H. Sakata、N. Nishida 等人：“通过扫描隧道光谱研究 CeRu2 中的涡晶格和准粒子态密度”J。

H.Sakata 他5名: "Imaging of a Vortex Lattice Transition in Yni_2B_2C by Scanning Tunneling Spectroscopy"Phys. Rev. Lett.. Vol.84,No.7. 1583-1586 (2000)

H. Sakata 和其他 5 人：“通过扫描隧道光谱对 Yni_2B_2C 中的涡旋晶格转变进行成像”Phys. Rev. Lett. 第 84 卷，第 1583-1586 期（2000 年）。