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SUMMARY:Universal fluctuating regime in triangular chromate pure Heisenber
 g S=3/2 antiferromagnets
DTSTART;VALUE=DATE-TIME:20220901T074000Z
DTEND;VALUE=DATE-TIME:20220901T080000Z
DTSTAMP;VALUE=DATE-TIME:20220826T121445Z
UID:indico-contribution-3640@indico.stfc.ac.uk
DESCRIPTION:Speakers: Philippe Mendels (Université Paris(Sacaly)\nThe ser
 ies of triangular compounds ACrO$_2$ is a model series for studying the He
 isenberg model on S=3/2 (Cr$^{3+}$: half-filled t$_{2g}$ orbitals) triangu
 lar antiferromagnets and the impact of interlayer couplings on the dynamic
 s. For this\, we report µSR measurements on α-HCrO$_2$ and KCrO$_2$ [1] 
 which complete former studies on the series of triangular compounds ACrO$_
 2$\, A = Li \, Na [2\, 3]. Coupled to $^1$H and $^{39}$K nuclear magnetic 
 resonance (NMR)\, we establish the static character at low-T\, as expected
  for a near neighbour Heisenberg model\, yet displaying a broad and remark
 able regime with slow fluctuations extending from $T_N$ down to 0.2 $T_N$.
  This regime is marked by a maximum in the μSR relaxation rate occuring a
 t 0.7 $T_N$\, associated with an NMR wipe-out .\nThe scaling of the NMR an
 d μSR data with respect to J or T$_N$ supports a scenario where a crossov
 er from 2D to 3D correlations sets in around 0.7 T$_N$ preceded by a typic
 al 2D regime of the TLHAF which appears to be a hallmark of the TLHAF with
  ABC stacking. We discuss the role of interlayer frustration which may bea
 r implications to recent spin-liquid candidates with the triangular geomet
 ry and exclude a scenario à la Berezinskii-Kostelitz-Touless of vortex-an
 tivortex topological excitations in that regime. In turn\, this underlines
  the crucial need  of further neighbour interactions\, anisotropy typical 
 of rare earth or even disorder to stabilize a quantum spin liquid state in
  triangular antiferromagnets such as YbMgGaO$_4$.\n[1] K. Somesh et al. Ph
 ys. Rev. B 104\, 104422 (2021).\n[2] A. Olariu et al. Phys. Rev. Lett. 97\
 , 167203 (2006).\n[3] A. Olariu et al. Phys. Rev. B 79\, 224401 (2009).\n\
 nhttps://indico.stfc.ac.uk/event/53/contributions/3640/
LOCATION:Science and Technology Campus\, University of Parma
URL:https://indico.stfc.ac.uk/event/53/contributions/3640/
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