Abstract
Co2V2O7 was recently reported to exhibit remarkable magnetic-field-induced magnetization plateaus and ferroelectricity [R. Chen, Phys. Rev. B 98, 184404 (2018)2469-995010.1103/PhysRevB.98.184404], but its magnetic ground state remains ambiguous. Magnetometry measurements and time-of-flight neutron powder diffraction (NPD) have been employed to study the structural and magnetic properties of Co2V2O7, which includes two nonequivalent Co sites. Upon cooling below the Néel temperature TN=6.0(2) K, we observe magnetic Bragg peaks at 2 K in NPD, which indicates the formation of long-range magnetic order of Co2+ moments. After symmetry analysis and magnetic structure refinement, we demonstrate that Co2V2O7 possesses a complicated noncollinear magnetic ground state with Co moments mainly located in the b-c plane and forming a noncollinear spin-chain-like structure along the c-axis. The ab initio calculations demonstrate that the noncollinear magnetic structure is more stable than various ferromagnetic states at low temperature. The noncollinear magnetic structure with a canted ↑↑↓↓ spin configuration is considered to be the origin of magnetoelectric coupling in Co2V2O7 because the inequivalent exchange striction induced by the spin-exchange interaction between the neighboring spins could be the driving force of ferroelectricity. It is also found that the deviation of lattice parameters a and b is opposite below TN, while the lattice parameter c and β stay almost constant below TN, evidencing the anisotropic magnetoelastic coupling in Co2V2O7.
| Original language | English |
|---|---|
| Article number | 134420 |
| Journal | Physical Review B |
| Volume | 100 |
| Issue number | 13 |
| DOIs | |
| State | Published - Oct 14 2019 |
| Externally published | Yes |
Funding
This work was supported by the National Natural Science Foundation of China (Grant No. 11874023) and Project Based Personnel Exchange Program (PPP) with China Scholarship Council (CSC Nos. 2016-6041) and German Academic Exchange Service (Project-ID 57219934). Part of the research conducted at SNS was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. W.H.J. would like to acknowledge financial support from the China Scholarship Council (CSC). The research at the University of Macau was supported by SRG2016-00091-FST and the Science and Technology Development Fund, Macau SAR (File no. 063/2016/A2, File no. 064/2016/A2, File no. 028/2017/A1, and File no. 0051/2019/AFJ). Work at Ames Laboratory was supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division, and the Office of Science Early Career Research Program. Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231.
| Funders | Funder number |
|---|---|
| Office of Basic Energy Sciences | |
| Scientific User Facilities Division | |
| U.S. Department of Energy Office of Science | |
| U.S. Department of Energy | SRG2016-00091-FST |
| Office of Science | |
| Basic Energy Sciences | |
| Iowa State University | |
| Division of Materials Sciences and Engineering | |
| Deutscher Akademischer Austauschdienst | 57219934 |
| National Natural Science Foundation of China | 11874023 |
| Science and Technology Development Fund | 064/2016/A2, 028/2017/A1, 0051/2019/AFJ, 063/2016/A2 |
| China Scholarship Council | 2016-6041 |