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Magnetic Phase Diagram of Magnetoelectric LiMnPO4



Rasmus Toft-Petersen, Niels H. Andersen, Haifeng Li, Jiying Li, Wei Tian, Sergey L. Bud'ko, Thomas B. S. Jensen, Christof Niedermayer, Mark Laver, Oksana Zaharko, Jeffrey W. Lynn, David Vaknin


The nature of the spin-flop (SF) transition in the magnetoelectric quasi-2D Heisenberg system LiMnPO4 is studied in fields applied along the a axis. A refinement of the magnetic structure using neutron diffraction data in the SF phase reveals that the spins re-orient from being parallel to the a- axis to be nearly along the c-axis at magnetic fields between 4 and 4.7T, depending on temperature. The low-field antiferromagnetic phase-boundry is shown to join the spin-flop line tangentially at the so-called bi-critical point, where there is a suppression of the ordering temperature. We observe an increased intentsity of the Lorentz broadened magnetic Bragg peaks above TN at the bi-critical fields as compated to zero field and 10 T, which is not accompanied by an increase in Lorentzian peak width. This suggests an increased density of fluctuations with short range order at the bi-critical field as compared to zero field.
Physical Review B


Multiferroic, Long range magnetic order, Magnetic field dependence, neutron diffraction, spin-flop transition, bicritical point


Toft-Petersen, R. , Andersen, N. , Li, H. , Li, J. , Tian, W. , Bud'ko, S. , Jensen, T. , Niedermayer, C. , Laver, M. , Zaharko, O. , Lynn, J. and Vaknin, D. (2012), Magnetic Phase Diagram of Magnetoelectric LiMnPO<sub>4</sub>, Physical Review B, [online], (Accessed February 27, 2024)
Created June 13, 2012, Updated October 12, 2021