Acta Phys. -Chim. Sin. ›› 2018, Vol. 34 ›› Issue (4): 437-444.doi: 10.3866/PKU.WHXB201709043

• ARTICLE • Previous Articles    

Point Defects Induced Ferromagnetism in Neutron Irradiated MgO(110) Single Crystals

Mengxiong CAO1,Xingyu WANG1,Yaru MA1,Chunlin MA1,Weiping ZHOU1,*(),Xiaoxiong WANG1,Haiou WANG2,Weishi TAN1,3,*()   

  1. 1 Key Laboratory of Soft Chemistry and Functional Materials of Ministry of Education, Department of Applied Physics, School of Science, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
    2 Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou 310018, P. R. China
    3 College of Communication and Electronic Engineering, Hunan City University, Yiyang 413002, Hunan Province, P. R. China
  • Received:2017-08-18 Published:2018-01-02
  • Contact: Weiping ZHOU,Weishi TAN E-mail:wpzhou@njust.edu.cn;tanweishi@njust.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(U1332106);the National Natural Science Foundation of China(11604147);the National Natural Science Foundation of China(11604067);Scientific Research Innovation Projects of Jiangsu Province for University Graduate Students, China(CXLX13_179)

Abstract:

The MgO(110) single crystals were neutron-irradiated with different doses ranging from 1.0×1016 to 1.0×1020 cm-2. The isointensity profiles of the X-ray diffuse scattering caused by the cubic and double-force point defects in MgO were calculated on the basis of the Huang scattering theory. The X-ray diffuse scattering and the UV-Vis absorption spectra were recorded to investigate the point defect configurations in the MgO(110) crystals. Furthermore, the magnetic properties were characterized by a superconducting quantum interference device magnetometer. The ω–2θ curves and rocking curves implied that neutron irradiation enhanced the lattice distortion. The point defects were produced in irradiated MgO crystals. The measured reciprocal space mappings (RSMs) revealed that the notable diffuse scattering was presented in irradiated MgO. Compared with the calculated diffuse scattering intensity profile, it was evident that Frenkel defects were introduced in the irradiated samples. The UV-Vis spectra indicated that anion O vacancy defects had been introduced in irradiated MgO. The single vacancies could be aggregated in irradiated samples with higher doses (1.0×1019 and 1.0×1020 cm-2). Although the irradiated MgO(110) single crystals were diamagnetic at room temperature, they became ferromagnetic at low temperature. The maximum saturation magnetization was found to be 0.058 emu·g-1. By means of neutron irradiation, defect-mediated ferromagnetism could be achieved at low temperature. The correlation between ferromagnetism and O vacancies in neutron-irradiated MgO could be described using F-center exchange mechanism.

Key words: MgO single crystal, Neutron irradiation, Point defect, d0 ferromagnetism, RSM, Color center

MSC2000: 

  • O649