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SUMMARY:Low-energy Excitations in Quantum Spin Liquid Derived from Molecul
 ar Mott Insulator
DTSTART;VALUE=DATE-TIME:20220901T070000Z
DTEND;VALUE=DATE-TIME:20220901T074000Z
DTSTAMP;VALUE=DATE-TIME:20220826T121442Z
UID:indico-contribution-3697@indico.stfc.ac.uk
DESCRIPTION:Speakers: Reizo Kato ()\nA molecular Mott insulator ß'-EtMe$_
 3$Sb[Pd(dmit)$_2$]$_2$ (dmit = 1\,3-Dithiol-2-thione-4\,5-dithiolate) is a
  quantum spin liquid (QSL) candidate. In the crystal with the space group 
 $C2/c$\, Pd(dmit)$_2$ anion radicals are strongly dimerized to form a dime
 r with spin 1/2. The dimers are arranged in an approximately isosceles-tri
 angular lattice\, which leads to a frustrated S = 1/2 Heisenberg spin syst
 em.\nThe system shows no magnetic order down to a very low temperature (~1
 9 mK) that corresponds to $J$/12\,000\, where $J$ (~250 K) is the nearest-
 neighbor spin interaction energy. The HOMO-LUMO mixing in the dimer unit i
 nduces fragmentation of S=1/2 electron spin with strong quantum fluctuatio
 n.\n Low-energy excitations in the QSL state are open to debate even now. 
 Heat capacity and magnetization indicate gapless fermion-like excitations\
 , while $^{13}$C-NMR indicates an existence of a nodal gap. ESR and µSR p
 robed the spinons\, revealing their gapless character and an unexpectedly 
 large degree of in-plane anisotropy in the spin dynamics. This anisotropic
  spin dynamics indicates quasi-one-dimensional diffusive motion in the dir
 ection of the weakest magnetic coupling in the triangular lattice.\n In 20
 10\, it was reported that thermal conductivity is characterized by its lar
 ge value and gapless behavior (a finite temperature-linear term). In 2019\
 , however\, two other research groups reported opposite data (much smaller
  value and a vanishingly small temperature-linear term) and the discrepanc
 y in the thermal conductivity measurement data emerges as a serious proble
 m concerning the ground state of QSL. An origin of the discrepancy will be
  discussed. \n\nI deeply thank all my collaborators\, especially\, H. Cui\
 , M. Uebe\, S. Fujiyama\, Y. Oshima\, I. Watanabe (RIKEN)\, Y. Nakazawa (O
 saka Univ.)\, Y. Ishii (Shibaura Institute of Technology) and F. L. Pratt 
 (STFC).\n\nhttps://indico.stfc.ac.uk/event/53/contributions/3697/
LOCATION:Science and Technology Campus\, University of Parma
URL:https://indico.stfc.ac.uk/event/53/contributions/3697/
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