N Mufti et al 2010 J. Phys.: Condens. Matter 22 075902 doi:10.1088/0953-8984/22/7/075902
N Mufti1,3, A A Nugroho1,2, G R Blake1 and T T M Palstra1
Show affiliationsWe have studied the magnetodieletric coupling of polycrystalline samples of the spinels MCr2O4 (M = Mn, Co and Ni). Dielectric anomalies are clearly observed at the onset of the magnetic spiral structure (Ts) and at the 'lock-in' transition (Tf) in MnCr2O4 and CoCr2O4, and also at the onset of the canted structure (Ts) in NiCr2O4. The strength of the magnetodielectric coupling in this system can be explained by spin–orbit coupling. Moreover, the dielectric response in an applied magnetic field scales with the square of the magnetization for all three samples. Thus, the magnetodielectric coupling in this state appears to originate from the P2M2 term in the free energy.
77.22.Ch Permittivity (dielectric function)
75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.)
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
Issue 7 (24 February 2010)
Received 3 November 2009, in final form 5 January 2010
Published 2 February 2010
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