Cu₂MgO₃ Electronic and Magnetic Properties – a DFT Study

Abstract

We investigate the properties of Guggenite-α Cu 2 MgO 3 , which has an experimentally measured energy gap of approximately 1 eV. The band gap of Cu 2 MgO 3 , which is in the solar spectrum range makes it a potential candidate for photovoltaic applications. We calculate with PBE + U and LDA + U, and the SCAN functionals, the structure, formation energy and electronic structure of Cu 2 MgO 3 in its antiferromagnetic ground state and in the ferromagnetic phase. Finally we discuss the formation energy and band gap dependence on the U-J Hubbard potential and compare our results to experiment.

Electronic and vibrational properties of MgCu2O3

“…The magnetic moment is different for two different groups of oxygen atoms (Table S1). Two of the oxygen atoms have a magnetic moment 0.096 , and four oxygen atoms have smaller moment 0.053 , which agrees with the work reported by Yekutiel et al 16 More details about the variation of magnetic moment and band gap values with the Hubbard parameter U can be seen in Table S1.…”

“…The PAW potentials treat the Cu‐3p 6 , 3d 10 , and 4s 1 , Mg‐2p 6 and 3s 2 , and O‐2s 2 and 2p 4 electrons as valance electrons. LDA and GGA‐PBE functionals predict MgCu 2 O 3 as metal, 15,16 but the electrical conductivity measurements show that MgCu 2 O 3 is a semiconductor 11 . In order to predict correct electronic properties in this highly correlated system, we have used DFT + U (Hubbard U correction) approach 16 introduced by Dudarev et al 29 We use the range of U from 0 eV to 9 eV in Cu d‐orbitals and examined the effect on electronic band structure and the magnetic moment on the Cu atoms.…”

“…Since the oxygen species O I and O II at the Wyckoff positions 4e and 2b, respectively, have different surroundings of the magnetic Cu atoms, the moment induced on these oxygen species is different. 16 The octahedron of CuO 6 shows Jahn-Teller distortion 14 (Figure 1b). It contains four planner oxygen atoms with a Cu-O distance between 1.955 and 2.034 Å and two apical oxygen atoms with bond lengths 2.515 and 2.749 Å.…”

“…The bond angles between the metal and oxygen atom are 166.1 and 170.0 in the a-b plane, whereas the bond angle in the b-c plane is 104.2 and 102.2 , which are near the previously reported values. 16 The Cu-O I -Cu bond in a-b plane gives a strong antiferromagnetic coupling between the two Cu atoms of the opposite spin and the Cu-O I -Cu in the b-c plane shows a weak ferromagnetic coupling between two Cu atoms of same spin. 18 Zeiske et al 11 have estimated the local magnetic moment on the Cu 2+ in the MgCu 2 O 3 to be 0.33 μ B by neutron diffraction method.…”

“…The LDA calculations predict MgCu 2 O 3 to be metallic. Yekutiel et al 16 computed the electronic and magnetic properties of the MgCu 2 O 3 compound with the DFT + U approach. They used LDA + U, PBE + U, and SCAN functionals to investigate the stability and electronic structure of the MgCu 2 O 3 compound in both ferromagnetic and antiferromagnetic spin configurations.…”