arXiv subjects

Swapnil M. Yadav

Publications and source records attributed to Swapnil M. Yadav.

2 recordsLinked to original sources

arXiv2023

Formation of random singlets in the nanocrystalline quasi-one-dimensional spin-1/2 antiferromagnet Sr21Bi8Cu2(CO3)2O41

Induced by quenched disorder, random-singlet states occur in a variety of low-dimensional spin-1/2 antiferromagnets, some of them candidates for quantum spin liquids. Here we report measurements of the specific heat, magnetization, and magnetic susceptibility of nanocrystalline Sr21Bi8Cu2(CO3)2O41, a quasi-one-dimensional spin-1/2 antiferromagnet with alternating bonds. The results uncover the predominant presence of random-singlet spin pairs in this material, with a logarithmic probability distribution, P(J), of the renormalized, emergent exchange interaction, J, in zero magnetic field and P(J) proportional to 1/J in magnetic fields. We postulate that these unexpected J dependences, in contrast to the usual P(J) \propto 1/$J^γ$ with 0 < $γ$ < 1, and possibly also the dichotomy, arise from the finite size of the nanocrystals. Scaling functions for the specific heat and magnetization reproduce our magnetocaloric-effect data, with no adjustable parameters.

cond-mat.str-el↗

arXiv2019

Finite field regime for a quantum spin liquid in $α$-RuCl$_3$

An external magnetic field can induce a transition in $α$-RuCl$_3$ from an ordered zigzag state to a disordered state that is possibly related to the Kitaev quantum spin liquid. Here we present new field dependent inelastic neutron scattering and magnetocaloric effect measurements implying the existence of an additional transition out of the quantum spin liquid phase at an upper field limit $B_u$. The neutron scattering shows three distinct regimes of magnetic response. In the low field ordered state the response shows magnon peaks; the intermediate field regime shows only continuum scattering, and above $B_u$ the response shows sharp magnon peaks at the lower bound of a strong continuum. Measurable dispersion of magnon modes along the $(0,0,L)$ direction implies non-negligible inter-plane interactions. Combining the magnetocaloric effect measurements with other data a $T-B$ phase diagram is constructed. The results constrain the range where one might expect to observe quantum spin liquid behavior in $α$-RuCl$_3$.

cond-mat.str-el↗