Manifestation of magnetic quantum fluctuations in the dielectric properties of a multiferroic.
Nat Commun
; 5: 4419, 2014 Jul 29.
Article
em En
| MEDLINE
| ID: mdl-25072808
ABSTRACT
Insulating magnets can display novel signatures of quantum fluctuations as similar to the case of metallic magnets. However, their weak spin-lattice coupling has made such observations challenging. Here we find that antiferromagnetic (AF) quantum fluctuations manifest in the dielectric properties of multiferroic Ba2CoGe2O7, where a ferroelectric polarization develops concomitant to an AF ordering. Upon application of a magnetic field (H), dielectric constant shows a characteristic power-law dependence near absolute zero temperature and close to the critical field Hc=37.1 T due to enhanced AF quantum fluctuations. When H>Hc, the dielectric constant shows the temperature-dependent anomalies that reflect a crossover from a field-tuned quantum critical to a gapped spin-polarized state. We uncover theoretically that a linear relation between AF susceptibility and dielectric constant stems from the generic magnetoelectric coupling and directly explains the experimental findings, opening a new pathway for studying quantum criticality in condensed matter.
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01-internacional
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MEDLINE
Idioma:
En
Revista:
Nat Commun
Ano de publicação:
2014
Tipo de documento:
Article