Bulk Sn1−xMnxO2 magnetic semiconductors without room-temperature ferromagnetism

Wide-bandgap dilute magnetic semiconductors (DMS), such as transition-metal doped ZnO and GaN , have gained attention for use in spintronic devices because of predictions and experimental reports of room temperature ferromagnetism which may enable their use in spintronic devices. However, there has been some debate over the source of ferromagnetism in these materials. This paper focuses on the high quality growth of wide bandgap DMS, and the characterization of Zn 1-x Mn x O produced by melt-growth techniques and Ga 1-x Mn x N grown by metal organic chemical vapor deposition (MOCVD). High resolution X-ray diffraction results revealed no second phases in either the ZnO crystals or the GaN films. Undoped as-grown, bulk crystals of Zn 1-x Mn x O and Zn 1-x Co x O crystals are shown to be paramagnetic at all temperatures. In contrast, the Ga 1-x Mn x N films showed ferromagnetic behavior at room temperature under optimum growth conditions. Experimental identification of the Mn ion charge state and the presence of bands in the bandgap of GaN are investigated by optical spectroscopy and electron spin paramagnetic resonance (EPR). It is shown that the broadening of states in the Mn 3d shell scaled with Mn concentration, and that optical transitions due to this band correlated with the strong ferromagnetism in these samples. However, this band disappeared with an increase in free electron concentration provided by either annealing or doping. Raman studies of Ga 1-x Mn x N revealed two predominant Mn -related modes featured with increasing concentration, a broad disorder related structure at 300cm-1 and a sharper peak at 669cm-1 This works show that the development of practical ferromagnetic wide bandgap DMS materials for spintronic applications will require both the lattice site introduction of Mn as well as careful control of the background defect concentration to optimize these materials.

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Manganese-vacancy complexes induced room temperature ferromagnetism in Mn/Mg co-doped In2O3 diluted magnetic semiconductors

Superlattices and Microstructures ◽

10.1016/j.spmi.2019.106174 ◽

2019 ◽

Vol 132 ◽

pp. 106174 ◽

Cited By ~ 1

Author(s):

Xiaocan Liu ◽

Shengrong Zhang ◽

Zhonghua Wu ◽

Yukai An

Keyword(s):

Room Temperature ◽

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Diluted Magnetic ◽

Co Doped

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Room temperature ferromagnetism in single-phase Zn1−x Mn x S diluted magnetic semiconductors fabricated by co-precipitation technique

Applied Physics A ◽

10.1007/s00339-017-0975-5 ◽

2017 ◽

Vol 123 (5) ◽

Cited By ~ 14

Author(s):

M. Hassan ◽

S. Younas ◽

F. Sher ◽

S. S. Husain ◽

S. Riaz ◽

...

Keyword(s):

Room Temperature ◽

Diluted Magnetic Semiconductors ◽

Single Phase ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Precipitation Technique ◽

Diluted Magnetic ◽

Co Precipitation

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Increased room temperature ferromagnetism in Co-doped tetrahedral perovskite niobates

Royal Society Open Science ◽

10.1098/rsos.210121 ◽

2021 ◽

Vol 8 (10) ◽

Author(s):

Yi Zhou ◽

Qing He ◽

Fei Zhou ◽

Xingqi Liao ◽

Yong Liu ◽

...

Keyword(s):

Room Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Dilute Magnetic Semiconductors ◽

Defect Band ◽

Co Doping ◽

Band Absorption ◽

Local Spin Polarization ◽

Curie Temperatures ◽

Co Doped

Dilute magnetic semiconductors (DMSs), such as (In, Mn)As and (Ga, Mn)As prototypes, are limited to III–V semiconductors with Curie temperatures ( T c ) far from room temperature, thereby hindering their wide application. Here, one kind of DMS based on perovskite niobates is reported. BaM x Nb (1− x ) O 3− δ ( M = Fe, Co) powders are prepared by the composite-hydroxide-mediated method. The addition of M elements endows BaM x Nb (1− x ) O 3− δ with local ferromagnetism. The tetragonal BaCo x Nb (1− x ) O 3− δ nanocrystals can be obtained by Co doping, which shows strong saturation magnetization ( M sat ) of 2.22 emu g −1 , a remnant magnetization ( M r ) of 0.084 emu g −1 and a small coercive field ( H c ) of 167.02 Oe at room temperature. The ab initio calculations indicate that Co doping could lead to a 64% local spin polarization at the Fermi level ( E F ) with net spin DOS of 0.89 electrons eV −1 , this result shows the possibility of maintaining strong ferromagnetism at room temperature. In addition, the trade-off effect between the defect band absorption and ferromagnetic properties of BaM x Nb (1− x ) O 3− δ is verified experimentally and theoretically.

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