High temperature carrier controlled ferromagnetism in alkali doped ZnO nanorods

Abstract

Recent efforts in developing spintronic and magneto-optoelectric material for applications have relied on the use of magnetic semiconductors doped with transition metals and have met with limited success. Using a fresh synthesis approach using alkali ions we demonstrate that alkali doped zinc oxide can provide high temperature magnetic semiconductors. We report studies on nanocrystalline powder and pellets of p-type ZnO:Li and ZnO:Na that exhibit ferromagnetism up to 554 K. The ferromagnetic behavior was confirmed from magnetic hysteresis, ferromagnetic resonance, magnetic force microscopy, and explained by a model where substitutional Li + / Na + in cation site induce local magnetic moments on oxygen atoms. Optimum dopant concentrations enable ferromagnetic exchange interaction leading to high Curie temperature.

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

“…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].…”

“…In order to eliminate these extrinsic magnetic behaviors, many researches have been focused on investigating the effect of nonmagnetic element doping in semiconductors. Recently, there have been reports of high-temperature ferromagnetism in some oxide and nitride semiconductors by doping nonmagnetic elements [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. 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 .…”

Influence of Co and Dy Doping on the Optical and Magnetic Properties of ZnO Nanoparticles for DMS Application

“…Transition metal-doped semiconductors have attracted a lot of attention due to their potential applications, such as UV detectors, field-effect transistors, short wavelength lasers, and high sensitive chemical sensors [2,3]. Santa Chawla et al demonstrated that alkali-doped zinc oxide also can provide high-temperature magnetic semiconductors (ZnO:Li and ZnO:Na) [4]. Soo et al reported the direct experimental evidence for III-V diluted magnetic semiconductors obtained by substitution doping of Mn impurities in InAs [5].…”

Nanoparticles and Fluorescence

“…Transition metal-doped ZnO NPs have shown dilute ferromagnetism [75]. Alkali atom (Li, Na) doping in ZnO nanorods made them p-type as well as ferromagnetic at room temperature and above [76,77]. White light emission and ferromagnetism have been observed in Sm 3+ -doped ZnO NPs synthesized by inclusive coprecipitation synthesis [78].…”