Magnetodielectric response of the spin-iceDy2Ti2O7

Abstract

We report the magnetodielectric response of single crystals of the spin-ice compound Dy 2 Ti 2 O 7 down to 0.26 K. The dielectric constant under zero magnetic field exhibits a clear decrease reflecting the development of the local two-spins-in, two-spins-out structure below about 1.2 K. Both the real and imaginary parts of the dielectric constant under magnetic fields sensitively respond to various changes in the spin structures. We found that the real part can be described in terms of local spin correlations among the moments of tetrahedra, rather than among individual Dy 3+ moments. Using the peaks in the imaginary part, we have constructed a precise field-temperature phase diagram in the ͓111͔ field direction. We thus demonstrate that the magnetodielectric response can be a high-sensitivity local probe of the spin state of geometrically frustrated systems.

Critical speeding-up in the magnetoelectric response of spin-ice near its monopole liquid–gas transition

“…We confirmed this magnetoelectricity in Dy 2 Ti 2 O 7 and, in addition, demonstrated that the dielectric dynamics gets dramatically modified close to the monopole liquid-gas transition resulting in a critical speeding-up. In order to confirm its precise link to monopoles, detailed measurements of the critical magnetic dynamics at frequencies extending 1 kHz are now called for 13 .…”

“…Full spectra of the dielectric response are presented in Fig. 3 for selected magnetic fields and temperatures in complete agreement with previously reported results 7 . The spectra contain a constant field-independent contribution to e 00 , which translates via the Kramers-Kronig relations to e 0 c:l: ðnÞ $ À ln n giving rise to a constant negative slope in the permittivity on a logarithmic frequency scale, see Supplementary Note 1.…”

“…The dynamics of the electric dipoles on magnetic monopoles thus leads to characteristic fluctuations of the electric polarization that, in principle, can be investigated with the help of the dielectric function e(n). First experimental indications for a magnetoelectric coupling in Dy 2 Ti 2 O 7 were reported by Saito et al 7 However, in their work the permittivity was only measured for a fixed frequency of 1 kHz. In the present work, we use broadband dielectric spectroscopy and present measurements of e(n) in Dy 2 Ti 2 O 7 for a wide range of frequencies, 1 Hzono1 MHz, and temperatures down to 200 mK.…”

New physics in frustrated magnets: Spin ices, monopoles, etc. (Review Article)

“…Other important experimental results for the magnetic field behavior of Dy 2 Ti 2 O 7 and Ho 2 Ti 2 O 7 the reader can find, e.g., in [142,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159]. …”

Magnetodielectric effect of Bi6Fe2Ti3O18film under an ultra-low magnetic field

“…The positive magnetodielectric responses below 55K in Figure 4b are attributable to that magnetic fields play a role of preventing low-temperature reduction in dielectric constants when nearest-neighbor spin correlation increases for antiferromagnetic structures [23].…”