Anish Koley | Searcharxiv

arXiv2026

The monopole plasma resonance: a smoking gun of 3D $U(1)$ quantum spin liquids

Certain 3D $U(1)$ spin liquids, such as those arising in dipolar quantum spin ice, have an emergent monopole which is the source of an emergent magnetic field that transforms under symmetries like an electric polarization. As a consequence, these monopoles carry a physical electric charge in their cores and form a plasma at low temperatures. Due to the monopole coupling to emergent gauge fields, the full system behaves as an electrical insulator for DC transport, but can display a sharp plasma resonance analogous to a metal at very low frequencies. This can serve as a clear fingerprint to detect these states in materials. We discuss the optimal conditions to observe this phenomenon in the 3D $U(1)$ spin-liquid candidate Ce$_2$Zr$_2$O$_7$.

cond-mat.str-el↗

arXiv2025

Vacancy induced expansion of spin-liquid regime in J1-J2 Heisenberg model

We study the model for spin-1/2 J1-J2 Heisenberg antiferromagnets on a square lattice in the presence of spin vacancies. In order to overcome the methodological challenges associated with analyzing models with magnetic frustration and inhomogeneities, we introduce a new semi-classical approach in which singlet dimers are treated as effective classical degrees of freedom. The energetic and entropic aspects of the dimer formation are included via a classical Monte Carlo scheme that allows for the dynamical conversion of spin pairs into dimers and vice versa. We show that our semi-classical approach recovers the qualitative physics of the J1-J2 model in the absence of vacancies. The vacancies lead to a broadening of the spin-liquid regime between the N\'eel and the stripe antiferromagnetic phases. This suggests a possible new route to discover spin-liquid ground states by tuning the J2/J1 ratio in doped square lattice antiferromagnets.

cond-mat.str-el↗