Critical speeding-up near the monopole liquid-gas transition in magnetoelectric spin-ice

Abstract

Competing interactions in the so-called spin-ice compounds stabilize a frustrated ground-state with finite zero-point entropy and, interestingly, emergent magnetic monopole excitations. The properties of these monopoles are at the focus of recent research with particular emphasis on their quantum dynamics. It is predicted that each monopole also possesses an electric dipole moment, which allows to investigate their dynamics via the dielectric function ε(ν). Here, we report on broadband spectroscopic measurements of ε(ν) in Dy2Ti2O7 down to temperatures of 200mK with a specific focus on the critical endpoint present for a magnetic field along the crystallographic [111] direction. Clear critical signatures are revealed in the dielectric response when, similarly as in the liquid-gas transition, the density of monopoles changes in a critical manner. Surprisingly, the dielectric relaxation time τ exhibits a critical speeding-up with a significant enhancement of 1/τ as the temperature is lowered towards the critical temperature. Besides demonstrating the magnetoelectric character of the emergent monopole excitations, our results reveal unique critical dynamics near the monopole condensation transition.

Changes: Data shown and discussed as function of internal field H and flux density B, Figs.3&4 rearranged, references added

References in corpus (6)

• Magnetization process of spin ice in a [111] magnetic field
• Electric dipoles on magnetic monopoles in spin ice
• Spin Dynamics at Very Low Temperature in Spin Ice Dy${}_2$Ti${}_2$O${}_7$
• Brownian Motion and Quantum Dynamics of Magnetic Monopoles in Spin Ice
• Thermal Conductivity and Specific Heat of the Spin-Ice Compound Dy${}_2$Ti${}_2$O${}_7$: Experimental Evidence for Monopole Heat Transport
• High temperature onset of field-induced transitions in the spin-ice compound Dy2Ti2O7

Cited by in corpus (13)

• The power of a critical heat engine
• Quantum quench dynamics
• Optimal cycles for low-dissipation heat engines
• Work and power fluctuations in a critical heat engine
• Multiferroicity in spin ice: towards a magnetic crystallography of Tb2Ti2O7 in a field
• Suppression of Pauling's Residual Entropy in Dilute Spin Ice (Dy${}_{1-x}$Y${}_x$)${}_2$Ti${}_2$O${}_7$
• Multiferroics and beyond: electric properties of different magnetic textures
• Experimental identification of electric dipoles induced by magnetic monopoles in Tb2Ti2O7
• Heat transport of the spin-ice materials Ho${}_2$Ti${}_2$O${}_7$ and Dy${}_2$Ti${}_2$O${}_7$
• Electric activity at magnetic moment fragmentation in spin ice
• Lattice dynamics and spin-phonon coupling in the kagome spin ice HoAgGe
• Exploring possible magnetic monopoles-induced magneto-electricity in spin ices
• Dynamic scaling near the Kasteleyn transition in spin ice: critical relaxation of monopoles and strings following a field quench