Magnetoelectric effects in single crystals of the cubic ferrimagnetic helimagnet Cu2OSeO3

Details Magnetoelectric effects in single crystals of the cubic ferrimagnetic helimagnet Cu2OSeO3 Magnetoelectric effects in single crystals of the cubic ferrimagnetic helimagnet Cu2OSeO3

2012-04-17

arxiv.org/abs/1204.3783v1

Physics

Condensed Matter

Strongly Correlated Electrons

Scientific paper

We present magnetodielectric measurements in single crystals of the cubic spin-1/2 compound Cu$_2$OSeO$_3$. A magnetic field-induced electric polarization ($\vec{P}$) and a finite magnetocapacitance (MC) is observed at the onset of the magnetically ordered state ($T_c = 59$ K). Both $\vec{P}$ and MC are explored in considerable detail as a function of temperature (T), applied field $\vec{H}_a$, and relative field orientations with respect to the crystallographic axes. The magnetodielectric data show a number of anomalies which signal magnetic phase transitions, and allow to map out the phase diagram of the system in the $H_a$-T plane. Below the 3up-1down collinear ferrimagnetic phase, we find two additional magnetic phases. We demonstrate that these are related to the field-driven evolution of a long-period helical phase, which is stabilized by the chiral Dzyalozinskii-Moriya term $D \vec{M} \cdot(\bs{\nabla}\times\vec{M})$ that is present in this non-centrosymmetric compound. We also present a phenomenological Landau-Ginzburg theory for the ME$_H$ effect, which is in excellent agreement with experimental data, and shows three novel features: (i) the polarization $\vec{P}$ has a uniform as well as a long-wavelength spatial component that is given by the pitch of the magnetic helices, (ii) the uniform component of $\vec{P}$ points along the vector $(H^yH^z, H^zH^x, H^xH^y)$, and (iii) its strength is proportional to $\eta_\parallel^2-\eta_\perp^2/2$, where $\eta_\parallel$ is the longitudinal and $\eta_\perp$ is the transverse (and spiraling) component of the magnetic ordering. Hence, the field dependence of P provides a clear signature of the evolution of a conical helix under a magnetic field. A similar phenomenological theory is discussed for the MC.

Affiliated with

Also associated with

No associations

Rating

Magnetoelectric effects in single crystals of the cubic ferrimagnetic helimagnet Cu2OSeO3 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Magnetoelectric effects in single crystals of the cubic ferrimagnetic helimagnet Cu2OSeO3, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetoelectric effects in single crystals of the cubic ferrimagnetic helimagnet Cu2OSeO3 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-289880