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SUMMARY:Studying spin diffusion and quantum entanglement with LF-$\\mu$SR
DTSTART;VALUE=DATE-TIME:20220829T090000Z
DTEND;VALUE=DATE-TIME:20220829T092000Z
DTSTAMP;VALUE=DATE-TIME:20220826T105641Z
UID:indico-contribution-3639@indico.stfc.ac.uk
DESCRIPTION:Speakers: Francis Pratt (STFC)\nLF-$\\mu$SR studies of spin di
 ffusion started with mobile solitons [1] and polarons [2] in conducting po
 lymers. Spin 1/2 antiferromagnetic chains can also support diffusive spin 
 excitations in a certain parameter range of the XXZ model [3]\, showing ei
 ther diffusive [4] or ballistic transport [5]. Recent LF-$\\mu$SR studies 
 of layered triangular lattice quantum spin liquid materials such as 1T-TaS
 $_2$ [6] and YbZnGaO$_4$ [7] have shown spin dynamics that is extremely we
 ll described by a 2D spin diffusion model\, fitting much better than previ
 ously proposed models for spin correlations. In YbZnGaO$_4$ the diffusion 
 rate shows a clear crossover between classical and quantum regimes as $T$ 
 falls below the exchange coupling $J$. That the spin diffusion approach wo
 rks well in the high $T$ classical region might be expected\, but it is fo
 und that it also works equally well in the low $T$ quantum region. This al
 lows a $T$ dependent length scale to be derived from the data that can be 
 assigned to a quantum entanglement length $\\xi$. Another entanglement mea
 sure\, the Quantum Fisher Information $F_Q$ [8] can also be obtained from 
 the LF-$\\mu$SR data and compared with $\\xi$.\n\n\n[1] K. Nagamine et al\
 , Phys. Rev. Lett. 53\, 1763 (1984)\; [2] F.L. Pratt et al\, Phys. Rev. Le
 tt. 79\, 2855 (1997)\; F.L. Pratt et al\, Physica B 326\, 34 (2003)\; [3] 
 B. Bertini et al\, Rev. Mod. Phys. 93\, 025003 (2021)\; [4] F.L. Pratt et 
 al\, Phys. Rev. Lett. 96\, 247203 (2006)\; F. Xiao et al\, Phys. Rev. B 91
 \, 144417 (2015)\; [5] T. Lancaster et al\, Phys. Rev. B 85\, 184404 (2012
 )\; B.M. Huddart et al\, Phys. Rev. B 103\, L060405 (2021)\; [6] S. Manas-
 Valero et al\, npj Quantum Mater. 6\, 69 (2021)\; [7] F.L. Pratt et al\, P
 hys. Rev. B 106\, L060401 (2022)\; [8] P. Hauke et al\, Nat. Phys. 12\, 77
 8 (2016).\n\nhttps://indico.stfc.ac.uk/event/53/contributions/3639/
LOCATION:Science and Technology Campus\, University of Parma
URL:https://indico.stfc.ac.uk/event/53/contributions/3639/
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