conclusion
Room-temperatureferrimagnetwith largemagnetism
P. S. Wang, H. J. Xiang*
Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, Collaborative Innovation Centerof Advanced Microstructures, and Department of Physics, Fudan University, Shanghai 200433, P. R. China
W. Ren
Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China
L. Bellaiche
Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
Predicting a Ferrimagnetic Phase of Zn2FeOsO6 with Strong
Magnetoelectric Coupling
Multiferroic materials, in which ferroelectric and magnetic ordering coexist, are of practical interest for the development of novel memorydevices that allow for electrical writing and non-destructive magnetic readout operation. The great challenge is to create room temperaturemultiferroic materials with strongly coupled ferroelectric and ferromagnetic (or ferrimagnetic) orderings. BiFeO3 is the most heavily investigatedsingle-phase multiferroic to date due to the coexistence of its magnetic order and ferroelectric order at room temperature. However, there is no netmagnetic moment in the cycloidal (antiferromagnetic-like) magnetic state of bulk BiFeO3, which severely limits its realistic applications in electricfield controlled memory devices. Here, we predict that LiNbO3-type Zn2FeOsO6 is a new multiferroic with properties superior to BiFeO3. First, thereare strong ferroelectricity and strong ferrimagnetism at room temperature in Zn2FeOsO6. Second, the easy-plane of the spontaneous magnetizationcan be switched by an external electric field, evidencing the strong magnetoelectric coupling existing in this system. Our results suggest thatferrimagnetic 3d-5d LiNbO3-type material may therefore be used to achieve voltage control of magnetism in future memory devices.
Abstract
novelmemorydevices :electricalwriting andmagneticreadout
Design room-temperature multiferroics
with strong magnetoelectric coupling
Large magnetic moment and
ferroelectric polarization
Motivations
systems
magnetism
T(K)
Polarization
BiFeO3
AFM
643
100
Zn2FeTaO6
AFM
22
50
Ca2FeOsO6
FIM
320
0
Some typical multiferroics
Zn2FeTaO6
Ca2FeOsO6
Zn2FeOsO6
High Tc;large M
R3 space group
54.7 uC/cm^2
GA search
Tolerance factor:
Zn2+displacement
Space group
R3
P21/n
C2
Energy(eV/f.u.)
0
0.09
0.22
0.45
R3 structure of Zn2FeOsO6
FiM structure of Zn2FeOsO6
2
Magnetic anisotropy in R3 Zn2FeOsO6
Exchange path
J1 (Fe-Os)
J2 (Fe-Os)
J3 (Os-Os)
J4 (Os-Os)
Effective J (meV)
31.68
29.62
7.25
3.24
Ferrimagneticstructure withFe and Osspins in theab plane
Easy plane: Single-ion anisotropy, AFe=0.89meV; AOs=-0.34meV
Spin canting: DM interaction,
Total energy curve is well described by the effective Hamiltonian
Thermodynamic properties of the magnetism
Tc=394K !!!
In-plane total spin moment: > 2
Space group
R3
P21/n
Tc(K)
394
344
356
Magnetoelectric coupling in Zn2FeOsO6
Double well potentialwith an energy barrierof 0.09eV/f.u.
Reference structure is
8 symmetrically equivalent<111> directions
71。or 109。switch of theFE domains by electric field
Strong ME coupling due to strong magnetic anisotropy !
1.Strong FE and strong FiM at room temperature in Zn2FeOsO6
2.The easy plane of the spontaneous magnetization can be switchedby an external electric field
For more information, see Phys. Rev. Lett. 114, 147204 (2015)