Antiferromagnetic phase transition in garnet-type AgCa2Mn2V3O12 and NaPb2Mn2V3O12 |
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Authors: | Junji Awaka Shuji Ebisu Masakazu Ito Shoichi Nagata |
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Institution: | 1. Department of Applied Sciences, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido 050-8585, Japan;2. Graduate School of Science and Engineering, Kagoshima University, Korimoto 1-21-35, Kagoshima 890-0065, Japan |
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Abstract: | Ferrimagnetism has been extensively studied in garnets, whereas it is rare to find the antiferromagnet. Present work will demonstrate antiferromagnetism in the two Mn–V-garnets. Antiferromagnetic phase transition in AgCa2Mn2V3O12 and NaPb2Mn2V3O12 has been found, where the magnetic Mn2+ ions locate only on octahedral A site. The heat capacity shows sharp peak due to antiferromagnetic order with the Néel temperature TN=23.8 K for AgCa2Mn2V3O12 and TN=14.2 K for NaPb2Mn2V3O12. The magnetic entropy change over a temperature range 0–50 K is 13.9 J K?1 mol-Mn2+-ions?1 for AgCa2Mn2V3O12 and 13.6 J K?1 mol-Mn2+-ions?1 for NaPb2Mn2V3O12, which are in good agreement with calculated value of Mn2+ ion with spin S=5/2. The magnetic susceptibility shows the Curie–Weiss behavior over the range 29–350 K. The effective magnetic moment μeff and the Weiss constant θ are μeff=6.20 μB Mn2+-ion?1 and θ=?34.1 K (antiferromagnetic sign) for AgCa2Mn2V3O12 and μeff=6.02 μB Mn2+-ion?1 and θ=?20.8 K for NaPb2Mn2V3O12. |
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