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Open Access Nano Express

Study of the oxygen vacancy influence on magnetic properties of Fe- and Co-doped SnO2 diluted alloys

Pablo D Borges1, Luisa M R Scolfaro2*, Horacio W Leite Alves3, Eronides F da Silva4 and Lucy V C Assali5

Author Affiliations

1 Instituto de Ciências Exatas e Tecnológicas, Universidade Federal de Viçosa - CRP, Rio Paranaíba, Minas Gerais, CP 38810-000, Brazil

2 Department of Physics, Texas State University, San Marcos, TX, 78666, USA

3 Departamento de Ciências Naturais, Universidade Federal de São João Del Rei, CP 110, São João Del Rei, Minas Gerais, 36301-160, Brazil

4 Departamento de Fisica, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil

5 Instituto de Fisica, Universidade de São Paulo, São Paulo, 05315-970, Brazil

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Nanoscale Research Letters 2012, 7:540  doi:10.1186/1556-276X-7-540

Published: 28 September 2012

Abstract

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 Sn0.96TM0.04O2 and Sn0.96TM0.04O1.98(VO)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 μB/cell, for Fe and Co. Two metastable states, with 0 and 4 μB/cell were found for Fe, and a single value, 3 μB/cell, for Co. The spin-crossover energies (ES) were calculated. The values are ES0/2 = 107 meV and ES4/2 = 25 meV for Fe. For Co, ES3/1 = 36 meV. By creating O vacancies close to the TM site, we show that the metastablity and ES change. For iron, a new state appears, and the state with zero magnetic moment disappears. The ground state is 4 μB/cell instead of 2 μB/cell, and the energy ES2/4 is 30 meV. For cobalt, the ground state is then found with 3 μB/cell and the metastable state with 1 μB/cell. The spin-crossover energy ES1/3 is 21 meV. Our results suggest that these materials may be used in devices for spintronic applications that require different magnetization states.

Keywords:
Tin dioxide; Diluted magnetic semiconductors; Magnetic properties; ab initio calculations; Electronic structure