Nonlinear magnetoelectric effect in paraelectric state of Co4Nb2O9 single crystal

Abstract

We report the structural, magnetoelectric (ME), magnetic and electric control of magnetic properties in Co4Nb2O9 (CNO) single crystal. A detailed ME measurement reveals a nonlinear ME effect instead of a linear ME effect in CNO single crystal. By fitting the magnetization-electric field (M-E) curve, it can be found that the linear () and quadratic (γ) coefficients equal to ~8.27 ps/m and ~−6.46 ps/MV for upper branch, as well as ~8.38 ps/m and ~6.75 ps/MV for the lower branch. More importantly, a pronounced response was observed under a small cooling magnetic field, which cannot even cause the spin flop. This suggests a magnetoelectric effect can occur at paraelectric state for CNO single crystal. Furthermore, we also found that the magnetization of every axis responds to electric field applied along a-axis, but fails to do so when the electric field is applied c-axis. Such findings supply a direct evidence to the magnetic structure and ME coupling mechanism indirectly reflected by our neutron experiment.

Spin dynamics and magnetoelectric coupling mechanism of Co4Nb2O9

“…We have measured the magnetization of single-crystal samples along different crystallographic axes. The results clearly show a cusp in the data measured along the a axis but no abnormality along the c axis near T N [11,14]. This suggests that the magnetic moments do not have components along the c axis, which is incompatible with the two magnetic structure models mentioned above.…”

Magnetic and structural properties of Ni-substituted magnetoelectric Co4Nb2O9

“…The family of M 4 A 2 O 9 (M = Co, Mn and A = Nb, Tb) compounds was initially reported by Fischer et al [11] to show a similar magnetoelectric coupling under application of a magnetic field below their magnetic ordering temperature. In recent years, several works have been published considering the magnetic, structural, and magnetoelectric features in this series of compounds [9,[12][13][14][15][16][17][18][19][20][21]. Among these compounds, Co 4 Nb 2 O 9 has been reported to show high magnetoelectric coupling at the vicinity of its Néel transition temperature [13,14,17].…”

“…In recent years, several works have been published considering the magnetic, structural and magnetoelectric features in this series of compound [9,[12][13][14][15][16][17][18][19][20][21]. Among these compounds, Co 4 Nb 2 O 9 has been reported to show high magnetoelectric coupling at the vicinity of its Neel transition temperature [13,14,17]. It crystallizes in the trigonal P 3c1 space group (No.…”

Spin dynamics, critical scattering and magnetoelectric coupling mechanism of Mn4Nb2O9

“…The crystal structure and the collinear magnetic structure with magnetic moments along the c axis were reported by Bertaut and his colleagues [13]. In recent years, Co 4 Nb 2 O 9 was discovered to demonstrate a high ME coefficient [14][15][16]. The origin of the ME effect in Co 4 Nb 2 O 9 was not clear when the property was reported.…”