Nonconventional magnetism in pristine and alkali doped In2O3: Density functional study

Abstract

Using In2O3 as a host matrix, extensive calculations based on density functional theory have been carried out to understand the electronic and magnetic properties of native defects, alkali and alkaline-earth metal substitutions as disputed in recent theoretical and experimental studies. Our calculations show that the magnetism in undoped In2O3 is originated from In vacancies (VIn) instead of O vacancies. The ferromagnetic (FM) coupling between the moments introduced by VIn is found strong enough to achieve room temperature ferromagnetism. Moreover, FM coupling is also strongly favored in alkali metal doping cases with negative formation energy. For all XIn (XIn=VIn, LiIn, NaIn, and KIn) doped In2O3, the induced magnetic moments are mainly localized on the first shell of O atoms around XIn sites. The FM coupling between the moments induced by XIn defects is activated by intra- and intercorrelation of the XIn–6ONN complexes. A XIn–ONN–InNN–ONN–XIn chain is required to mediate the long-range FM coupling. However, in cases of Mg or Ca doped In2O3, the ground state is nonmagnetic.

Possible ferromagnetism in Li, Na and K-doped AlN: A first-principle study

“…2 reveals that most of the spin density is localized in the vicinity of the dopant and its nearest neighboring N atoms, with a small contribution from the farther N atoms. Similar moment distributions have been found in Mg and Ca doped AlN [49,50], Mg, K, Al and Sr doped SnO 2 [43,44], Li doped TiO 2 [46] and alkali doped In 2 O 3 [45]. To study the magnetic coupling between the moments induced by doping, the systems Al 34 X 2 N 36 (X¼ Li, Na and K), in which two Al atoms are substituted by doping atoms X in the supercell, are investigated.…”

“…3-5, the 2p states of the N atoms overlap significantly near the Fermi level, suggesting a strong p-p hybridization interaction between them [29]. It has been reported that the introduced holes in 2p orbitals of the N atoms can couple with each other through this strong interaction [29,45]. Indeed, the calculated spin density in Fig.…”

“…1. As mentioned above, first-principle calculations suggested that the substitutional alkali atom at cation site can induce ferromagnetism in several oxides and nitrides [28,[44][45][46][47]. Similarly, calculation by Bouzerar cation in dioxides by monovalent cation of group 1A of the periodic table would be a promising direction for stabilizing or increasing the Curie temperature experimentally [54].…”

“…At the same time, first-principle calculations showed that appropriate nonmagnetic anion or cation substitutions in several oxide, nitride or sulfide semiconductors can induce intrinsic ferromagnetism . In this respect, alkali metal was theoretically predicted to be potential nonmagnetic dopant for some semiconductors [28,[44][45][46][47], and ferromagnetism has been reported in alkali metal doped ZnO and SnO 2 [24][25][26][27]. Moreover, wurtzite AlN is one of the promising host semiconductors in the field of spintronics, and it has been reported that nonmagnetic Si, Sc and Cu doped AlN are ferromagnetic above room temperature [19][20][21].…”

Stabilizing intrinsic defects in SnO2

“…7 Recently, several experimental and theoretical reports showed that cation vacancies can induce magnetism not only in SnO 2 , but also in ZnO, TiO 2 , ZrO 2 , In 2 O 3 , CeO 2 , and HfO 2 . [8][9][10][11][12][13] Following the prediction of magnetism without TM impurities, much interest was also diverted to magnetism induced by light element doping in host semiconductor matrices, e.g., K, N, Mg, and C-doped SnO 2 . [14][15][16][17][18] There are experimental evidences which clearly demonstrate room temperature FM induced by light elements.…”