title: Coupled ferroelectric polarization and magnetization in spinel FeCr2S4.
abstract: One of the core issues for multiferroicity is the strongly coupled ferroelectric polarization and magnetization, while so far most multiferroics have antiferromagnetic order with nearly zero magnetization. Magnetic spinel compounds with ferrimagnetic order may be alternative candidates offering large magnetization when ferroelectricity can be activated simultaneously. In this work, we investigate the ferroelectricity and magnetism of spinel FeCr2S4 in which the Fe(2+) sublattice and Cr(3+) sublattice are coupled in antiparallel alignment. Well defined ferroelectric transitions below the Fe(2+) orbital ordering temperature Too = 8.5 K are demonstrated. The ferroelectric polarization has two components. One component arises mainly from the noncollinear conical spin order associated with the spin-orbit coupling, which is thus magnetic field sensitive. The other is probably attributed to the Jahn-Teller distortion induced lattice symmetry breaking, occurring below the orbital ordering of Fe(2+). Furthermore, the coupled ferroelectric polarization and magnetization in response to magnetic field are observed. The present work suggests that spinel FeCr2S4 is a multiferroic offering both ferroelectricity and ferrimagnetism with large net magnetization.
authors.affiliation: 1] Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China [2] Department of Physics, Southeast University, Nanjing 211189, China.
authors.forename: L
authors.initials: L
authors.lastname: Lin
authors.affiliation: Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: H X
authors.initials: HX
authors.lastname: Zhu
authors.affiliation: Institute for Quantum Materials, Hubei Polytechnic University, Huangshi 435100, China.
authors.forename: X M
authors.initials: XM
authors.lastname: Jiang
authors.affiliation: Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: K F
authors.initials: KF
authors.lastname: Wang
authors.affiliation: Department of Physics, Southeast University, Nanjing 211189, China.
authors.forename: S
authors.initials: S
authors.lastname: Dong
authors.affiliation: Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Z B
authors.initials: ZB
authors.lastname: Yan
authors.affiliation: Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Z R
authors.initials: ZR
authors.lastname: Yang
authors.affiliation: Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: J G
authors.initials: JG
authors.lastname: Wan
authors.affiliation: Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: J-M
authors.initials: JM
authors.lastname: Liu