Exploring multiferroicity, half-metallic phase, and curie temperature in X = B/C/N/F-Doped KNbO3: a DFT aspect

Abstract

Abstract Multiferroic materials provide an astonishing platform for next-generation spintronic devices such as magnetoresistive random access memory. Herein, ferroelectric, electronic, and magnetic properties of the pristine and X = B/C/N/F-doped KNbO3 (KNO) perovskite oxides are explored using ab initio calculations along with modified Becke-Johnson potential, where X is doped at O-site (X@O) in both KO- and NbO2-layers. Our calculations revealed that the pristine motif is a non-magnetic insulator having an energy band gap (E g ) of 2.80 eV and spontaneous polarization (P) of 41 μCcm−2, which are close to the experimentally observed values of 3.34 eV and 37 μCcm−2, respectively. The computed enthalpy of formation and elastic parameters confirm the thermodynamic and mechanical strength of the doped configurations, respectively. It is established that X-dopants significantly reduce structural distortions and have negative influence on the value of P. The most distinctive feature of the current work is that the B/N-doped KNO system for X@O in the KO-layer exhibits n-type half-metallic (HM) ferromagnetic (FM) behavior with an E g of 1.46/2.96 eV which is sufficiently large enough to prevent any magnetic transition. In contrast, C and F-doped structures are FM insulator and n-type non-magnetic metallic, respectively. Along with this, X = B/C/N-doped KNO system for X@O in the NbO2-layer displayed FM insulating nature, while the F-doped motif becomes an n-type non-magnetic metallic. The total magnetic moment for the B/N-doped structure is 1.0, which also hints the HM FM behavior. Finally, the estimated Curie temperature using the Heisenberg 2D Hamiltonian model in magnetic doped structures is found to be high enough to be used for practical purposes.