Tuning the metamagnetism in a metallic helical antiferromagnet.

Authors :: Ma, S. C.
Liu, K.
Ma, C. C.
Ge, Q.
Zhang, J. T.
Hu, Y. F.
Liu, E. K.
Zhong, Z. C.
Source :: Applied Physics Letters. 12/4/2017, Vol. 111 Issue 23, p1-5. 5p. 1 Diagram, 3 Graphs.
Publication Year :: 2017
Abstract: The antiferromagnetic (AFM)-ferromagnetic (FM) conversion in martensite was observed in Mn/Ni-substitution upon FM elements, such as Fe or Co, in MnNiGe helical antiferromagnets. Here, we report an AFM-FM conversion and consequently a sharp magnetic-field-driven metamagnetic martensitic transformation from paramagnetic (PM) austenite to FM martensite in the Ni- and Mnsubstituted MnNiGe alloys with indium, a non-magnetic and large-sized main group element. Accordingly, a giant magnetocaloric effect such that a twofold increase of the magnetic entropy change in MnNi0.92GeIn0.08 and even a nearly threefold increase in the Mn0.92NiGeIn0.08 alloy is obtained with respect to the MnNiGe0.95In0.05 alloy. The origin of AFM-FM conversion and resultantly sharp magnetic-field-induced PM-FM metamagnetic transformation is discussed based on the first-principles calculations and X-ray absorption spectroscopic results. [ABSTRACT FROM AUTHOR]