Recent research topics (examples)

Development of the novel two-dimensional NMR technique to probe the correlation between the local spin susceptibility (probed by the NMR Knight shift) and the local low energy spin excitations (probed by the NMR relaxation rate 1/T1), and its application in the research into the disorder effects in a proximate quantum spin liquid realized in Zn-barlowite.   W. Yuan, J. Wang et al., npj Quantum Materials 7, 120 (2022).

63Cu NQR investigation of the ground state of the proximate kagome quantum spin-liquid material, "Zn-barlowite" ZnCu3(OH)6FBr.  We found direct evidence for the emergence of spin singlets in the kagome plane by applying the novel Inverse Laplace transform (ILT) T1 analysis technique that we have recently introduced to quantum condensed matter physics.  J. Wang, W. Yuan et al., Nature Physics 17, 1109-1113 (2021).

139La NMR investigation of the charge order phenomenon in copper-oxide high temperature superconductor La1.875Ba0.125CuO4 based on the novel Inverse Laplace transform (ILT) T1 analysis technique,  in collaboration with the Imai group alumnus Dr. P. Singer (Rice University) and Prof. M. Fujita (Tohoku University).  P. M. Singer et al., Physical Review B 101, 174508 (2020).

63Cu NQR and NMR investigation of Cu2IrO3, a candidate material of Kitaev spin liquid. S.K. Takahashi et al., Physical Review X 9, 031047 (2019).

17O single crystal NMR demonstration of the gapped spin excitations in herbertsmithite kagome Heisenberg antiferromagnet ZnCu3(OH)6Cl2.  Mingxuan Fu's Ph.D. dissertation work, in collaboration with Prof. Y. S. Lee's group at Stanford. M. Fu et al., Science 350, 655 (2015). Also read the Physics Today article about our discovery.

75As NMR investigation of exotic superconductivity in the Cr3As3 sub-nano tube in K2Cr3As3.  Haizhao Zhi's M.Sc. work, in collaboration with Prof. G. Cao's group at Zhejiang University. H. Zhi et al., Physical Review Letters 114, 147004 (2015).

75As and 63Cu  NMR investigation of the quantum critical point in Cu-substituted iron-pnictide high temperature superconductor BaFe2As2.  Dr. H. Takeda's postdoctoral work, in collaboration with Dr. A. Sefat's group at Oak Ridge National Lab and Prof. B. Gaulin's group at McMaster. H. Takeda et al., Physical Review Letters 113, 117001 (2014).

93Nb NMR investigation of the quantum critical point in the transverse field Ising chain CoNb2O6, in collaboration with Prof. S. Sachdev at Harvard and Prof. G. Luke at McMaster published as Physical Review X4, 031008 (2014).  Also read the highlighting article in Physics Viewpoint published online by the American Physical Society.

77Se NMR investigation of the phase diagram and spin fluctuations in pressure-induced high temperature superconductivity in FeSe, in collaboration with Prof. R.J. Cava at Princeton University.  The NMR measurements were conducted by Dr. Imai himself 2008-2009, non-stop through the winter holiday season. T. Imai et al., Physical Review Letters, 102, 177005 (2009).

Search for the link between spin fluctuations associated with the spin density wave instability and the superconducting mechanism in Ba(Fe1-xCox)2As2 high temperature superconductor, in collaboration with Oak Ridge National Lab. and Chinese Academy of Sciences / Nanjing University. F. L. Ning et al., Physical Review Letters, 104, 037001 (2010). F. L. Ning et al., J. Phys. Soc. Jpn. 77 103705 (2009); ibid 78 013711 (2009). Also read the Physics Today article about our discovery (Fig.3 is from Fanlong's thesis work).