|PLACE||R203, 2F, NCTS, NCKU|
|SPEAKER||Prof. Jason S Gardner - Bloomington and NIST Center for Neutron Research, Indiana University, USA|
|TITLE||Hunt for new spin-1/2, frustrated systems|
|ABSTRACT||Quantum spin liquid (QSL) in which magnetic spins remain disordered in the limit of
zero Kelvin, underpins much of modern condensed matter theory.
Previous studies have shown that QSL ground states tend to emerge in the geometrically frustrated materials and the organic salts K-BEDT-TTF)2Cu2(CN)3, EtnMe4-nSb[Pd(DMIT)2]2 and ZnCu3(OH)6Cl2. [1-3] may be good candidates. Two different experimental programs have begun to look for other systems where spin ½ ions occupy a triangular motif. One family under investigation is the intercalated derivatives of Znsubstituted copperhydroxy-nitrate (CHN) , Cu2(1-x)Zn2x(OH)3NO3, the other is the inorganic compound Ba3CuSb2O9.
To date the bulk properties of polycrystalline samples have been performed and small single crystals have been grown. These data will be presented along with some preliminary neutron scattering work that is currently underway.
If time permits I will discuss recent work on new pyrochlore oxides that exhibit ideal spin ice behaviour and correlated magnetic monopoles below 1 K.
This work is done in collaboration with Chris Wiebe (Winnipeg, Canada), Haidong Zhou (FSU), Jian Wu, Fletcher Werner, Julia S. Wildeboer, Alexander Seidel, Zohar Nussinov and Stuart A. Solin (Wahsington University in St Louis).
References S. Yamashita et al., Nature Phys. 4, 459 (2008). M. Yamashita et al., Science 328, 1246 (2010). J. S. Helton et al., Phys. Rev. Lett. 98, 107204 (2007). G. G. Linder et al., J. Solid State Chem. 116 1 (1995)