清大物理---先進奈米薄膜實驗室


	*Researchs Interest*

		�研究方向

	Half metal ferromagnet
	Since half metals in principle provide conducting electrons with only one polarization of spins, they have been intensively studied to enhance the performance of spintronics. Half metals are magnetically oriented compounds for which the electrons of one spin orientation have metal-like energy bands, whereas electrons of the opposite spin encounter an energy gap about the Fermi energy. Since half metals, by definition, have electrons of only one spin state present at the Fermi energy, they are logical candidates for use as spin injectors.
	The DOS of four types half-metallic ferromagnetic oxides [ J. M. D. Coey et al., J. Phys. D: Appl. Phys. 35, 2457(2002) ]
	Density of states for Fe₃O₄ and CrO₂ in calculations:
[M. A. Korotin et al., Phys. Rev. Lett.80, 4305(1998)]

Experimental verification of half-metallic spin polarization of the conduction electrons, has proven more intractable. The measurement techniques available are spin-polarized photoemission, transport measurements point contacts or tunnel junctions between two spin-polarized materials, and Andreev reflection between the candidate half metal and a superconductor. Below are the typical experimental results:


	We propose to investigate the spin transport behavior of half metals in ferrimagnetic spinel system. Our objective is to obtain a high quality epitaxial films using MBE system for spintronic devices. The spin resolved photoemission, measured at NSRRC, will be used for quantitative characterization of the spin polarization factor in half metal films.