[1] Walailak Univ, Magnet Lab, Sch Sci, Nakhon Si Thammarat 80161, Thailand
[2] Khon Kaen Univ, Dept Phys, Fac Sci, Khon Kaen 40002, Thailand
[3] Kasetsart Univ, Dept Phys, Fac Sci, Bangkok 10900, Thailand
[4] Natl Met & Mat Technol Ctr MTEC, Pathum Thani 12120, Thailand
[5] Suranaree Univ Technol, Inst Sci, Sch Phys, Nakhon Ratchasima 30000, Thailand