Random Coulomb antiferromagnets: from diluted spin liquids to Euclidean random matrices

Rehn, J. ; Sen, Arnab ; Andreanov, A. ; Damle, Kedar ; Moessner, R. ; Scardicchio, A. (2015) Random Coulomb antiferromagnets: from diluted spin liquids to Euclidean random matrices Physical Review B: Condensed Matter and Materials Physics, 92 (8). Article ID 085144. ISSN 2469-9950

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Official URL: http://journals.aps.org/prb/abstract/10.1103/PhysR...

Related URL: http://dx.doi.org/10.1103/PhysRevB.92.085144


We study a disordered classical Heisenberg magnet with uniformly antiferromagnetic interactions which are frustrated on account of their long-range Coulomb form, i.e., J(r)∼−Alnr in d=2 and J(r)∼A/r in d=3. This arises naturally as the T→0 limit of the emergent interactions between vacancy-induced degrees of freedom in a class of diluted Coulomb spin liquids (including the classical Heisenberg antiferromagnets in checkerboard, SCGO, and pyrochlore lattices) and presents a novel variant of a disordered long-range spin Hamiltonian. Using detailed analytical and numerical studies we establish that this model exhibits a very broad paramagnetic regime that extends to very large values of A in both d=2 and d=3. In d=2, using the lattice-Green-function-based finite-size regularization of the Coulomb potential (which corresponds naturally to the underlying low-temperature limit of the emergent interactions between orphans), we find evidence that freezing into a glassy state occurs only in the limit of strong coupling, A=∞, while no such transition seems to exist in d=3. We also demonstrate the presence and importance of screening for such a magnet. We analyze the spectrum of the Euclidean random matrices describing a Gaussian version of this problem and identify a corresponding quantum mechanical scattering problem.

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ID Code:103879
Deposited On:09 Mar 2018 11:31
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