First-principle study of magnetism in Co-doped SnO2 (original) (raw)
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2020
Due to their potential application in the field of spintronics, the discovery of various types of oxide-based dilute magnetic semiconductors (ODMS) materials that might work at practical room temperature ferromagnetism (RTFM) has recently attracted great attention. Among ODMS materials, transition metalTM doped tin oxide (SnO2) compounds are important for the investigation of ferromagnetism due to its special important property such as high chemical stability, high carrier density, n-type behavior and trait long range ferromagnetism. However, the question of understanding the mechanism of ferromagnetism (FM) process is still not fully understood in these materials, due to unable to know exactly whether its FM property arises from the nature of the intrinsic property or secondary phases of the material. According to the results from many literature surveys, the mechanism of magnetic ordering responsible for magnetic exchange interaction in these materials is highly affected by oxygen...
Effect of Annealing Temperature on the Magnetic Properties of Co-Doped Sno 2
2014
Annealing temperature plays a very crucial role in the surface morphology and magnetic properties of Co doped SnO 2. In this paper, we present a systematic investigation of the effect of annealing temperature on the magnetic properties of Co doped SnO 2. Sn 1-x Co x O 2 samples have been chemically synthesized with low Co concentration (≤ 1%). The X-ray diffraction (XRD), and scanning electron microscopy (SEM), are used to characterize these samples. The XRD pattern shows the tetragonal rutile structure. The crystallite size and the average particle size increases with increase in annealing temperature. The samples sintered at 350 o C, 450 o C and 550 o c show ferromagnetism at room temperature while those sintered at ≥ 600 o C show paramagnetism. With the increase of annealing temperature, the ferromagnetism observed at room temperature in the low temperature sintered samples is gradually suppressed and finally completely removed. This destruction of ferromagnetism at higher anneal...
Journal of Magnetism and Magnetic Materials, 2019
In this paper, the challenge is to investigate the possibility to have the ferromagnetic or/and ferrimagnetic behavior connected to Sn 0.98 Mn 0.02 (O 1-x C x) 2 system at low concentration (x = 0.02, 0.03, 0.04 and 0.05) at room temperature (RT). We utilized the Korringa-Kohn-Rostoker method combined with the Coherent Potential Approximation (KKR-CPA). The Cdoped SnO 2 induced the half-metallic characteristic located on the Fermi level and the presence of the double-exchange coupling type belongs to the ferromagnetic (FM). The Sn 0.98 Mn 0.02 O 2 shows the antiferromagnetic (AFM) stability belongs to super-exchange coupling type. For Sn 0.98 Mn 0.02 (O 1-x C x) 2 system, we predicted two statements, the presence of the FM stability where (x = 0.03) and the ferrimagnetic stability where (x = 0.02, 0.04, 0.05). The Curie temperature (T C) can be estimated within the mean field approximation (MFA), our calculations predicted 358.45 K for Sn(O 0.95 C 0.05) 2 and 402.26 K for Sn 0.98 Mn 0.02 (O 0.95 C 0.05) 2. The ferrimagnetic materials are useful for many applications.
Vacancy-induced magnetism in SnO2: A density functional study
We study the magnetic and electronic properties of defects in SnO2 using pseudopotential and all electron methods. Our calculations show that bulk SnO2 is non-magnetic, but it shows magnetism with a magnetic moment around 4.00 µB due to Sn vacancy (VSn). The magnetic moment comes mainly from O atoms surrounding VSn and Sn atoms, which couple antiferromagnetically with the O atoms in the presence of VSn. The coupling between different Sn vacancies is also studied and we find that these defects not only couple ferromagnetically but also antiferromagnetically and ferrimagnetically. Our calculations demonstrate that the experimentally observed giant magnetic moment of transition metal doped SnO2 can be attributed to VSn. PACS numbers: 75.50.Pp, 61.72.Ji, 71.22.+i In many diluted magnetic semiconductor (DMS) the non-magnetic matrix is a conventional compound semiconductor such as GaAs 1 or InAs 2 . These DMSs have low solubility limit and their Curie temperatures (T C )s are well below room temperature (RT), which disqualify them for spintronic devices. In other classes of DMS the transition metal (TM) is embedded in oxide semiconductors, which are conventionally known as oxide-DMS (ODMS), such as ZnO with Co or Mn doping 3,4,5 , TiO 2 (anatase) with Co 6 and SnO 2 with Co 7 . These ODMSs have large magnetic moments and their T C s are well above RT. Therefore these are good candidates for spintronic devices.
Study of the oxygen vacancy influence on magnetic properties of Fe- and Co-doped SnO2 diluted alloys
Nanoscale Research Letters, 2012
Transition-metal (TM)-doped diluted magnetic oxides (DMOs) have attracted attention from both experimental and theoretical points of view due to their potential use in spintronics towards new nanostructured devices and new technologies. In the present work, we study the magnetic properties of Sn 0.96 TM 0.04 O 2 and Sn 0.96 TM 0.04 O 1.98 (V O ) 0.02 , where TM = Fe and Co, focusing in particular in the role played by the presence of O vacancies nearby the TM. The calculated total energy as a function of the total magnetic moment per cell shows a magnetic metastability, corresponding to a ground state, respectively, with 2 and 1 μ B /cell, for Fe and Co. Two metastable states, with 0 and 4 μ B /cell were found for Fe, and a single value, 3 μ B /cell, for Co. The spin-crossover energies (E S ) were calculated. The values are E S 0/2 = 107 meV and E S 4/2 = 25 meV for Fe. For Co, E S 3/1 = 36 meV. By creating O vacancies close to the TM site, we show that the metastablity and E S change. For iron, a new state appears, and the state with zero magnetic moment disappears. The ground state is 4 μ B /cell instead of 2 μ B /cell, and the energy E S 2/4 is 30 meV. For cobalt, the ground state is then found with 3 μ B /cell and the metastable state with 1 μ B /cell. The spin-crossover energy E S 1/3 is 21 meV. Our results suggest that these materials may be used in devices for spintronic applications that require different magnetization states.
Structural, electronic, and magnetic properties of Co doped SnO2 nanoparticles
We present a detailed study on the structural, electronic, and magnetic properties of chemically synthesized Sn 1−x Co x O 2 ͑x = 0.00 to 0.05͒ nanoparticles. X-ray diffraction and transmission electron microscope measurements were performed to analyze the crystal structure and morphology of Sn 1−x Co x O 2 nanoparticles. The energy dispersive x-ray analysis measurements were performed to check the possible presence of any impurity elements in the nanocrystals. The near edge x-ray absorption fine structure ͑NEXAFS͒ experiments at Sn M 5,4 -edge and Co L 3,2 -edge were performed to probe the local environment of Sn and Co ions in the SnO 2 matrix. The NEXAFS at Co L 3,2 -edge, along with multiplet calculations, indicate that the Co is substituted at the Sn site in SnO 2 matrix with +2 charge state and do not form metallic clusters and other oxide phases. The ferromagnetic nature of these materials was confirmed by x-ray magnetic circular dichroism and room temperature magnetization hysteresis loop measurements.
The Journal of Physical Chemistry C, 2015
We present here an ab initio study of the structural, magnetic, and hyperfine properties of Fe-doped rutile SnO 2 for different concentrations and distributions of the Fe atoms and oxygen vacancies in the SnO 2 host. The calculated results are compared with experimental ones obtained by Mossbauer spectroscopy and X-ray absorption techniques. This comparison enables us to characterize the local structure around Fe atoms and to identify the different hyperfine interactions that are observed in samples prepared by different methods. It is concluded that oxygen vacancies are fundamental for the ferromagnetic response of Fe-doped SnO 2. The ab initio calculations show that two Fe ions sharing an oxygen vacancy are coupled ferromagnetically, forming a bound magnetic polaron (BMP), and that two neighbor BMPs are aligned antiparallel to each other. Electron doping plays a fundamental role mediating the magnetic coupling between the BMP inducing ferromagnetic alignment between the BMPs.
Magnetization Enhancement in Room-Temperature Ferromagnetic Fe–Mn Co-Doped SnO 2
Japanese Journal of Applied Physics, 2012
Dilutely Fe-Mn co-doped SnO 2 was synthesized by a sol-gel method. The co-doping effect enhances the magnetization in comparison with the case of single-ion doping. We found that saturation magnetization values are correlated with the crystalline sizes. Mö ssbauer spectrometry revealed the magnetic sextet and relaxation peaks, which suggest that Fe ions contribute to the magnetic ordering and superparamagnetic properties. X-ray absorption spectroscopy revealed that Mn 3þ states mixed with Mn 2þ states are dominant in Fe-Mn co-doped SnO 2 .