Scientists of a joint research team in China proposed a new structurally perfect quantum spin liquids (QSLs) candidate YbMgGaO4 for the first time, which is unique and excellent for future QSLs research.
Quantum spin liquids (QSLs) are novel phases of matter, where quantum spin fluctuations prevent any conventional spin freezing even at 0K, despite the significant spin-spin interactions. Studies on QSLs have aroused great interest of researchers in condensed matter physics since the resonating valence bond (RVB) states were proposed by Anderson in 1980s.
These years, there are extensive studies on the most famous QSLs candidates, such as ZnCu3(OH)6Cl2, k-(ET)2Cu2(CN)3 and Yb2Ti2O7. However, some unavoidable structural “shortcomings”, such as magnetic defects, lattice distortions and Dyaloshinskii-Moriya (DM) interactions, make extraction of the intrinsic physics from a real magnet difficult and lead to serious research divergence. As a result, the structurally perfect QSLs candidates remain in urgent need.
The joint research team finds many structural advantages of the new candidate YbMgGaO4 over previously reported candidates. This new proposed candidate has perfect triangular lattices with R-3m symmetries and the concentration of magnetic defects is negligible (<0.04%). Moreover, the antisymmetric DM interactions are symmetrically forbidden and the interlayer magnetic interactions are negligible, compared to the intralayer nearest neighboring interactions. As for this candidate, it is available to gain both high-quality single crystals and the nonmagnetic reference single-crystals LuMgGaO4 for control experiments, such as extraction of the magnetic heat capacities from the total heat capacities of YbMgGaO4. Furthermore, the Kramers ground state double is well separated from the first excited double by an energy gap ~ 420K for Yb3+ ions. It has an odd number of electrons per unit cell and it performs as a good insulator. All these factors make YbMgGaO4 an ideal candidate for QSLs research.
With the cooperation with Prof. CHEN Gang from Fudan University, the study was conducted by a joint research group led by Dr. LI Yuesheng and Prof. ZHANG Qingming of Renmin University of China by using the Electron Spin Resonance spectrometer (ESR), 3He-Magnetic Property Measurement System (MPMS) and low-temperature X-ray Diffractometer (XRD) in the Steady High Magnetic Field Facilities (SHMFF) in High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences and dilution refrigerator Physical Property Measurement System (PPMS) in Fudan University.
The above findings were published in Scientific. Reports. with title Gapless quantum spin liquid ground state in the two-dimensional spin-1/2 triangular antiferromagnet YbMgGaO4. and Physical Review Letters with title Rare-Earth Triangular Lattice Spin Liquid: A Single-Crystal Study of YbMgGaO4.
Contact:
LI Yuesheng
Department of Physics, Renmin University of ChinaBeijing 100872, P. R. China
liyuesheng@ruc.edu.cn
ZHANG Qingming
Department of Physics, Renmin University of China
Beijing 100872, P. R. China
qmzhang@ruc.edu.cn
CHEN Gang
Department of Physics, Fudan University
Shanghai 200433, P. R. China
chggst@gmail.com
