High Impact Work by UROP Student

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Using a combined experimental and theoretical approach, it was demonstrated recently that Li doping in ZnO can lead to room temperature ferromagnetism (Yi et al, Phys. Rev. Lett. 104, 137201 (2010)). This was a joint effort between Prof. Feng’s group in Physics Department and Prof. Ding’s group in Materials Science and Engineering Department. It is worth noting that the computational work that contributed to the understanding of physical mechanism of the room temperature ferromagnetism was carried out by an undergraduate student, Mr. Lim Chin Chean, as part of his UROPs project, Jan – Dec 2009. It is generally believed that cation vacancy can lead to ferromagnetism in oxide such as ZnO. However, the formation energy of cation vacancy is typically high which prevents a high concentration of cation vacancy at room temperature. In this work, the authors demonstrated that incorporating Li in ZnO can reduce the formation energy of Zn vacancy, by forming defect complex. In addition to provide practical way of producing dilute magnetic semiconductor, this work demonstrates that defects can be controlled and engineered to tune the properties of engineering materials.