Existence of electron and hole pockets and partial gap opening in the correlated semimetal Ca3Ru2O7

作     者：Hui Xing Libin Wen Chenyi Shen Jiaming He Xinxin Cai Jin Peng Shun Wang Mingliang Tian Zhu-An Xu Wei Ku Zhiqiang Mao Ying Liu 

作者机构：Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education) and Shanghai Center for Complex Physics School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Department of Physics Zhejiang University Hangzhou 310027 China Department of Physics and Materials Research Institute Pennsylvania State University University Park Pennsylvania 16802 USA Department of Physics and Engineering Physics Tulane University New Orleans Louisiana 70118 USA High Magnetic Field Laboratory Chinese Academy of Sciences Hefei 230031 China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 China 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2018年第97卷第4期

页      面：041113(R)-041113(R)页

核心收录：

基　　金：CAS/SAFEA National Science Foundation, NSF U.S. Department of Energy, USDOE Office of Experimental Program to Stimulate Competitive Research, EPSCoR, (DE-SC0012432) Office of Experimental Program to Stimulate Competitive Research, EPSCoR Louisiana Board of Regents Pennsylvania State University, PSU National Natural Science Foundation of China, NSFC, (11474198, 11774305, 91421304, EFMA1433378, U1332209) National Natural Science Foundation of China, NSFC Chinese Academy of Sciences, CAS, (U1432251) Chinese Academy of Sciences, CAS Ministry of Science and Technology of the People's Republic of China, MOST, (2015CB921104) Ministry of Science and Technology of the People's Republic of China, MOST Shanghai Jiao Tong University, SJTU Fundamental Research Funds for the Central Universities 

主　　题：Fermi surface Nernst effect Thermoelectric effects Thermopower Ruthenates 

摘      要：The electronic band structure of correlated Ca3Ru2O7 featuring an antiferromagnetic (AFM) as well as a structural transition has been determined theoretically at high temperatures, which has led to the understanding of the remarkable properties of Ca3Ru2O7, such as the bulk spin-valve effects. However, its band structure and Fermi surface (FS) below the structural transition have not been resolved, even though a FS consisting of electron pockets was found experimentally. Here we report magnetoelectrical transport and thermoelectric measurements with the electric current and temperature gradient directed along the a and b axes, respectively, of an untwined single crystal of Ca3Ru2O7. The thermopowers obtained along the two crystal axes were found to show opposite signs at low temperatures, demonstrating the presence of both electron and hole pockets on the FS. In addition, how the FS evolves across T*=30K at which a distinct transition from coherent to incoherent behavior occurs was also inferred: the Hall and Nernst coefficient results suggest a temperature- and momentum-dependent partial gap opening in Ca3Ru2O7 below the structural transition with a possible Lifshitz transition occurring at T*. The experimental demonstration of a correlated semimetal ground state in Ca3Ru2O7 calls for further theoretical studies of this remarkable material.