Observation of magnetic field-induced second magnetic ordering and peculiar ferroelectric polarization in L-type ferrimagnetic Fe2(MoO4)3

D Chandrasekhar Kakarla^1*, Ajay Tiwari¹, M.-J. Hsieh², J.-Y Lin², C. W. Wang³, L. K. Tseng¹, C. E. Lu¹, Arkadeb Pal¹, T. W. Kuo¹, Mitch M. C. Chou^4,5, H. D. Yang^1,5

¹Department of Physics, National Sun Yat-sen University, Kaohsiung, 8042, Taiwan
²Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
³National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
⁴Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
⁵Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan

* Presenter:D Chandrasekhar Kakarla, email:chandu@g-mail.nsysu.edu.tw

Fe₂(MoO₄)₃ was synthesized and characterized as a prototype of L-type ferrimagnets (L-FiM) with an ordering temperature T_N1 ~ 12 K using magnetic susceptibility (χ), specific heat (Cp), and dielectric (ε) anomaly. Two remarkable findings are magnetic field (H) induced (I) an additional magnetic phase transition at T_N2 below T_N1; and (II) the emergence of flexible ferroelectric polarization (P) with the tuning parameters H and T below T_N2. Thus, the H-T phase diagram for spin-induced type-II multiferroics was established. In contrast to some known multiferroics with a critical field-induced spin-flip P below T_N1, the observed multiferroic nature is exotic. The origin of the profound multiferroic nature may be hidden in the complex T-and H-dependent spin and lattice structures. Consequently, the schematic picture of H- induced possible change of lattice symmetry and conical spin structure has been proposed. More experimental and theoretical works providing solid evidence and interpretations have been suggested to explore these peculiar multiferroic phenomena.

Keywords: L-type ferrimagnetism, Magnetic field-induced multiferroic, Ferroelectric polarization.