Minki Jeong wins best poster award

© 2015 EPFL
Minki's poster entitled Dipolar-Coupled Heisenberg Spin System LiGdF4 awarded best poster at the 20th International Conference on Magnetism in Barcelona.
LQM was represented at 20th ICM in Barcelona by several group members, engaging in scientific discussions and starting new collaborations. Minki's poster on LiGdF4 presenting work together with Peter Babkevich and Ivan Kovacevic attracted considerable interest, including that of the poster award committee.
Dipolar-coupled heisenberg spin system LiGdF4
M. Jeong, I. Kovacevic, P. Babkevich, A. Di Lieto, H. M. Ronnow
The LiRF4 family is rare systems of purely dipolar-coupled magnets. In particular, LiGdF4 does not possess orbital angular momentum so that the crystal field interaction vanishes. This situation is completely different from other family members such as LiHoF4 and LiErF4 where the crystal field determines the spin
symmetry and interaction sign at low temperatures: Ising ferromagnetic and XY antiferromagnetic, respectively. The competition between ferromagnetic and antiferromagnetic characters of dipolar interactions in LiGdF4 may lead new and unconventional low-temperature phases. We investigate this unique dipolar-coupled Heisenberg system with ac susceptibility and muSR measurements. A rich set of phases both as a function of temperature below 0.2 K and a field below 1 T is evidenced by the ac susceptibility. Local probe muSR measurements further show that these low temperature phases are magnetically long-range ordered. This complex phase diagram makes strong contrast to the simple ones of LiHoF4 [1] and LiErF4 [2].
[1] H. M. Ronnow et al., Science 308, 389 (2005)
[2] C. Kraemer et al., Science 336, 1416 (2012)