### Session T33: Novel Magnetic Materials

2:30 PM–5:30 PM, Wednesday, March 17, 2010
Room: E143

Chair: Yves Idzerda, Montana State University

Abstract ID: BAPS.2010.MAR.T33.3

### Abstract: T33.00003 : Origin of Giant Saturation Magnetization in Fe$_{16}$N$_{2}$ thin film

2:54 PM–3:06 PM

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#### Authors:

Jian-Ping Wang
(Center for Micromagnetics and Information Technologies, University of Minnesota)

Nian Ji
(Center for Micromagnetics and Information Technologies, University of Minnesota)

Xiaoqi Liu
(Center for Micromagnetics and Information Technologies, University of Minnesota)

Yunhao Xu
(Center for Micromagnetics and Information Technologies, University of Minnesota)

C. Sanchez-Hanke
(NSLS, Brookhaven National Laboratory)

Can localized 3d electron exist in strong ferromagnetic metal because of some unusual correlation effect? This question is related to the controversy on whether $\alpha$''- Fe$_{16}$N$_{2}$ has giant saturation magnetization which has been debated for decades since its first observation$^{1,2}$. Here we report the synthesis of $\alpha$''- Fe$_{16}$N$_{2}$ thin films. The highest moment is obtained to be 3.0$\mu _{B}$/Fe. XMCD experiment is systematically performed on a series of iron nitrides samples. Among all the iron nitrides phases, it is found that there exist highly localized 3d electrons only in chemically disordered Fe$_{8}$N and ordered F$_{16}$N$_{2}$ phases$^{3}$. This discovery hints at the origin of the giant magnetic moment is correlated with the 3d electron localization in such system. First principle calculation (LDA+U) further verifies that the d electron localization is the key element to rationalize the high moment formation in iron nitrides system$^{4}$. We also provide a speculative outlook on the giant saturation magnetization formation based on cluster + atom'' concept. 1.Kim, T.K. and Takahashi. M, Appl. Phys. Lett., 20, 492 (1972) 2.Sugita, Y., et al., J. Appl. Phys. 76, 6637 (1994) 3.Liu, X. Q. et al., arxiv: 0909.4480 (2009) 4.Ji, N. et al., arxiv: 0909.4478 (2009)

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.T33.3