Enhanced spin correlations in the Bose-Einstein condensate compound Sr3Cr2O8

Abstract

Combined experimental and modeling studies of the magnetocaloric effect, ultrasound, and magnetostriction were performed on single-crystal samples of the spin-dimer system Sr${}_3$Cr${}_2$O${}_8$ in large magnetic fields, to probe the spin-correlated regime in the proximity of the field-induced XY-type antiferromagnetic order also referred to as a Bose-Einstein condensate of magnons. The magnetocaloric effect, measured under adiabatic conditions, reveals details of the field-temperature ($H,T$) phase diagram, a dome characterized by critical magnetic fields $H_{c1}$ = 30.4 T, $H_{c2}$ = 62 T, and a single maximum ordering temperature $T_{\max }(45$T$)\simeq$8 K. The sample temperature was observed to drop significantly as the magnetic field is increased, even for initial temperatures above $T_{\max }$, indicating a significant magnetic entropy associated to the field-induced closure of the spin gap. The ultrasound and magnetostriction experiments probe the coupling between the lattice degrees of freedom and the magnetism in Sr${}_3$Cr${}_2$O${}_8$. Our experimental results are qualitatively reproduced by a minimalistic phenomenological model of the exchange-striction by which sound waves renormalize the effective exchange couplings.

arXiv comment9 pages, 14 figures

References in corpus (14)

• Bose-Einstein Condensation in Magnetic Insulators
• Realization of Bose-Einstein condensation of dilute magnons in TlCuCl${}_3$
• Field-induced Bose-Einstein Condensation of triplons up to 8 K in Sr3Cr2O8
• High resolution magnetostriction measurements in pulsed magnetic fields using Fibre Bragg Gratings
• Quantum fluctuations and strong mass renormalization in NiCl2-4SC(NH2)2
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• Adiabatic measurements of magneto-caloric effects in pulsed high magnetic fields up to 55 T
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• Character of magnetic excitations in a quasi-one-dimensional antiferromagnet near the quantum critical points: Impact on magneto-acoustic properties
• Adiabatic physics of an exchange-coupled spin-dimer system: magnetocaloric effect, zero-point fluctuations, and possible two-dimensional universal behavior
• Asymmetric Thermal Lineshape Broadening in a Gapped 3-Dimensional Antiferromagnet - Evidence for Strong Correlations at Finite Temperature
• Orbital fluctuations and orbital order below the Jahn-Teller transition in Sr3Cr2O8
• Coupled spin-lattice fluctuations in a compound with orbital degrees of freedom: the Cr based dimer system Sr3Cr2O8
• Highly sensitive simple homodyne phase detector for ultrasonic pulse-echo measurements

Cited by in corpus (7)

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• Neutron diffraction of field-induced magnon condensation in the spin-dimerized antiferromagnet Sr${}_3$Cr${}_2$O${}_8$
• Investigating field-induced magnetic order in Han Purple by neutron scattering up to 25.9 T
• Magnetoelastic coupling at the field-induced transition in EuAl${}_{12}$O${}_{19}$
• Dominant Kitaev Interaction and Field-induced Quantum Disordered Phase in the Cobaltate Na${}_2$Co${}_2$TeO${}_6$