Signatures of field-induced Berezinskii-Kosterlitz-Thouless correlations in the three-dimensional manganite Bi0.5Sr0.5Mn0.9Cr0.1 O3

Ashoka, A and Bhagyashree, KS and Bhat, SV (2020) Signatures of field-induced Berezinskii-Kosterlitz-Thouless correlations in the three-dimensional manganite Bi0.5Sr0.5Mn0.9Cr0.1 O3. In: Physical Review B, 102 (2).

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Abstract

Despite experimental evidence for the two-dimensional topological Berezinskii-Kosterlitz-Thouless (BKT) transition in superconducting films and He4 superfluid films, the observation of a BKT transition in condensed matter systems has proven to be difficult. Potential signatures of BKT transitions were reported in two-dimensional magnets, however, the observation of a classical BKT transition in nominally three-dimensional systems has naturally not been investigated as the transition requires an underlying XY model with spins confined to a plane. Here we report that the temperature dependence of the electron paramagnetic resonance (EPR) linewidth observed in Bi0.5Sr0.5Mn1-xCrxO3 (x=0.1 and 0.04) as well as in certain other three-dimensional (3D) manganites undergoing antiferromagnetic transitions is described satisfactorily by the BKT model. We explain this unexpected observation of signatures of a two-dimensional topological phase transition in 3D systems in terms of an effective two-dimensional XY easy plane anisotropy induced by the magnetic field applied in the EPR experiment that allows for the mediation of long-range vortex-like correlations between spin clusters formed due to phase segregation. This conclusion is supported by a re-analysis of EPR results reported earlier in La-doped CaMnO3 and a nonmanganite compound BaNi2V2O8. We infer that field-induced BKT correlations in a 3D system provide a step towards the observation of a BKT transition in a suitably chosen condensed matter system by the application of an appropriate magnetic field. © 2020 American Physical Society.

Item Type:	Journal Article
Publication:	Physical Review B
Publisher:	American Physical Society
Additional Information:	The copyright of this article belongs to American Physical Society
Keywords:	Barium compounds; Calcium compounds; Condensed matter physics; Electron energy analyzers; Electron spin resonance spectroscopy; Lanthanum compounds; Magnetic fields; Manganites; Nickel compounds; Paramagnetic resonance; Superconducting films; Temperature distribution; Topology, Antiferromagnetic transition; Berezinskii-Kosterlitz-Thouless transition; Condensed matter system; Electron paramagnetic resonances (EPR); Temperature dependence; Three dimensional systems; Threedimensional (3-d); Two-dimensional magnet, X-Y model
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	31 Aug 2020 09:53
Last Modified:	31 Aug 2020 09:53
URI:	http://eprints.iisc.ac.in/id/eprint/66425

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