Orbital glass conceals missing magnetic entropy in a relativistic Mott insulator

Fuente: arXiv
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Bibliographic Details
Main Authors: Nikolov, Ilija K., Cong, Rong, Rosuel, Adrien, Carr, Stephen, Fisher, Ian R., Feldman, Dmitri E., Del Maestro, Adrian, Ramanathan, Chandrasekhar, Mitrović, Vesna F.
Format: Preprint
Published: 2026
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author Nikolov, Ilija K.
Cong, Rong
Rosuel, Adrien
Carr, Stephen
Fisher, Ian R.
Feldman, Dmitri E.
Del Maestro, Adrian
Ramanathan, Chandrasekhar
Mitrović, Vesna F.
author_facet Nikolov, Ilija K.
Cong, Rong
Rosuel, Adrien
Carr, Stephen
Fisher, Ian R.
Feldman, Dmitri E.
Del Maestro, Adrian
Ramanathan, Chandrasekhar
Mitrović, Vesna F.
contents Coupling between different degrees of freedom (DOF) in an electronic material leads to exotic phases of matter characterized by complex and competing order parameters as well as emergent excitations. Building a microscopic understanding of these order parameters and their mutual relationship is hindered by the fact that different orders often mask each others' response to conventional experimental probes. Here, we reveal how to disentangle responses from distinct orders that arise from the coupling between the spin and orbital DOF. Our method uses a phase sensitive technique that measures ground state properties by independently resolving interactions of different symmetries. This allows us to directly detect an orbital glass state caused by competing interactions in the $5d^1$ relativistic Mott insulator Ba$_2$NaOsO$_6$. We observe short-range orbital order up to 380 K and a dramatic increase of orbital dispersion near the magnetic phase transition. This orbital dispersion generates a directional ordering, $\textit{i.e.}$, it forms an orbital nematic state which breaks the rotational symmetry of the crystal. We establish that the orbital nematic state induces the magnetic ordering. The presence of this short-range orbital order well above the magnetic phase transition solves the long-standing puzzle of missing entropy in this material.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17540
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Orbital glass conceals missing magnetic entropy in a relativistic Mott insulator
Nikolov, Ilija K.
Cong, Rong
Rosuel, Adrien
Carr, Stephen
Fisher, Ian R.
Feldman, Dmitri E.
Del Maestro, Adrian
Ramanathan, Chandrasekhar
Mitrović, Vesna F.
Strongly Correlated Electrons
Coupling between different degrees of freedom (DOF) in an electronic material leads to exotic phases of matter characterized by complex and competing order parameters as well as emergent excitations. Building a microscopic understanding of these order parameters and their mutual relationship is hindered by the fact that different orders often mask each others' response to conventional experimental probes. Here, we reveal how to disentangle responses from distinct orders that arise from the coupling between the spin and orbital DOF. Our method uses a phase sensitive technique that measures ground state properties by independently resolving interactions of different symmetries. This allows us to directly detect an orbital glass state caused by competing interactions in the $5d^1$ relativistic Mott insulator Ba$_2$NaOsO$_6$. We observe short-range orbital order up to 380 K and a dramatic increase of orbital dispersion near the magnetic phase transition. This orbital dispersion generates a directional ordering, $\textit{i.e.}$, it forms an orbital nematic state which breaks the rotational symmetry of the crystal. We establish that the orbital nematic state induces the magnetic ordering. The presence of this short-range orbital order well above the magnetic phase transition solves the long-standing puzzle of missing entropy in this material.
title Orbital glass conceals missing magnetic entropy in a relativistic Mott insulator
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2604.17540