Magnetic phase transitions in Pr(1-x)LuxMn(2)Ge(2) compounds

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Institute of Physics
The effects of replacing Pr by Lu on the magnetic behaviour and structures of Pr1-xLuxMn2Ge2 (x = 0.2, x = 0.4) have been investigated using x-ray diffraction, Mossbauer spectroscopy, magnetization and neutron diffraction measurements. The substitution of Lu for Pr leads to a decrease in the lattice constants a, c and the unit cell volume V at room temperature with this contraction of the unit cell resulting in modifications of the Pr1-xLuxMn2Ge2 magnetic structures. Four and five magnetic phase transitions-linked primarily with temperature driven changes in the intralayer Mn-Mn separation distances-have been detected within the temperature range 4.5-550 K for Pr0.8Lu0.2Mn2Ge2 and Pr0.6Lu0.4Mn2Ge2, respectively, with re-entrant ferromagnetism being detected around T-C(Pr) similar to 31 K for Pr0.6Lu0.4Mn2Ge2. Itwas found that T-C(inter) and T-C(Pr) increase with increasing applied field while T-N(inter) decreases for Pr0.6Lu0.4Mn2Ge2, indicating that the canted antiferromagnetic AFmc region contracts with increasing field. The Debye temperatures for Pr1-xLuxMn2Ge2 with x = 0.2 and 0.4 were evaluated as theta(D) = 320 +/- 40 K and theta(D) = 400 +/- 20 K respectively from the temperature dependence of the average isomer shift. The magnetic structures of both compounds have been determined by means of neutron diffraction measurements over the temperature range 3-300 K with formation of the Fmi magnetic state below Tc/c = 192 K for Pr0.8Lu0.2Mn2Ge2 and the occurrence of re-entrant ferromagnetism below T-C(Pr) = 31 K for Pr0.6Lu0.4Mn2Ge2 being confirmed. © 2009, Institute of Physics
Ferromagnetism, Neutron diffraction, X-ray diffraction, Spectroscopy, Magnetization, Intermetallic compounds
Wang, J. L., Campbell, S. J., Studer, A. J., Avdeev, M., Zeng, R., & Dou, S. X. (2009). Magnetic phase transitions in Pr(1-x)LuxMn(2)Ge(2) compounds. Journal of Physics: Condensed Matter, 21(12), 124217. doi:10.1088/0953-8984/21/12/124217