Dynamical magnetism in the disordered cubic lattice material $γ$-${\rm Ba}_{3}{\rm CoNb}_{2}{\rm O}_{9}$

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Main Authors: Xu, Fanjun, Feyerherm, Ralf, Glittum, Cecilie, Hicken, Thomas J., Luetkens, Hubertus, Krieger, Jonas A., Aguilar-Maldonado, Cintli, Luther, Sven, Saunders, Lucy K., Ritter, Clemens, Fouquet, Peter, Russina, Margarita, Prokes, Karel, Islam, A. T. M. Nazmul, Lake, Bella
Format: Preprint
Published: 2026
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author Xu, Fanjun
Feyerherm, Ralf
Glittum, Cecilie
Hicken, Thomas J.
Luetkens, Hubertus
Krieger, Jonas A.
Aguilar-Maldonado, Cintli
Luther, Sven
Saunders, Lucy K.
Ritter, Clemens
Fouquet, Peter
Russina, Margarita
Prokes, Karel
Islam, A. T. M. Nazmul
Lake, Bella
author_facet Xu, Fanjun
Feyerherm, Ralf
Glittum, Cecilie
Hicken, Thomas J.
Luetkens, Hubertus
Krieger, Jonas A.
Aguilar-Maldonado, Cintli
Luther, Sven
Saunders, Lucy K.
Ritter, Clemens
Fouquet, Peter
Russina, Margarita
Prokes, Karel
Islam, A. T. M. Nazmul
Lake, Bella
contents $γ$-${\rm Ba}_{3}{\rm CoNb}_{2}{\rm O}_{9}$ realizes a disordered simple-cubic spin-$1/2$ lattice in which Co$^{2+}$ ions randomly occupy one third of the sites, placing the system close to the site-percolation threshold for magnetic order. Specific-heat, susceptibility, neutron spin-echo, and muon spin-rotation measurements reveal a broad thermodynamic crossover, short-range magnetic correlations, and persistent fast spin dynamics down to at least 0.1~K, with no evidence for static order or conventional spin-glass freezing. Monte Carlo simulations yield a broad distribution of orphan spins, finite clusters, and an infinite network. The calculated orphan-spin fraction ($\approx 8.8\%$) agrees well with the weakly correlated spin fraction inferred from magnetization ($\approx 8.2\%$). Exact diagonalization of a diluted $S = 1/2$ Heisenberg model captures the broad magnetic specific-heat anomaly and supports the coexistence of weakly and strongly correlated spin environments. These results support a picture in which spin-$1/2$ quantum fluctuations, together with dilution and proximity to the percolation threshold, can support a disorder-driven dynamical state with short-range correlations in three dimensions, distinct from both classical spin glasses and geometrically frustrated quantum spin liquids.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18794
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Dynamical magnetism in the disordered cubic lattice material $γ$-${\rm Ba}_{3}{\rm CoNb}_{2}{\rm O}_{9}$
Xu, Fanjun
Feyerherm, Ralf
Glittum, Cecilie
Hicken, Thomas J.
Luetkens, Hubertus
Krieger, Jonas A.
Aguilar-Maldonado, Cintli
Luther, Sven
Saunders, Lucy K.
Ritter, Clemens
Fouquet, Peter
Russina, Margarita
Prokes, Karel
Islam, A. T. M. Nazmul
Lake, Bella
Strongly Correlated Electrons
Materials Science
$γ$-${\rm Ba}_{3}{\rm CoNb}_{2}{\rm O}_{9}$ realizes a disordered simple-cubic spin-$1/2$ lattice in which Co$^{2+}$ ions randomly occupy one third of the sites, placing the system close to the site-percolation threshold for magnetic order. Specific-heat, susceptibility, neutron spin-echo, and muon spin-rotation measurements reveal a broad thermodynamic crossover, short-range magnetic correlations, and persistent fast spin dynamics down to at least 0.1~K, with no evidence for static order or conventional spin-glass freezing. Monte Carlo simulations yield a broad distribution of orphan spins, finite clusters, and an infinite network. The calculated orphan-spin fraction ($\approx 8.8\%$) agrees well with the weakly correlated spin fraction inferred from magnetization ($\approx 8.2\%$). Exact diagonalization of a diluted $S = 1/2$ Heisenberg model captures the broad magnetic specific-heat anomaly and supports the coexistence of weakly and strongly correlated spin environments. These results support a picture in which spin-$1/2$ quantum fluctuations, together with dilution and proximity to the percolation threshold, can support a disorder-driven dynamical state with short-range correlations in three dimensions, distinct from both classical spin glasses and geometrically frustrated quantum spin liquids.
title Dynamical magnetism in the disordered cubic lattice material $γ$-${\rm Ba}_{3}{\rm CoNb}_{2}{\rm O}_{9}$
topic Strongly Correlated Electrons
Materials Science
url https://arxiv.org/abs/2604.18794