Magnetoresistance and magnetization processes in the helimagnetic compound DyMn6Ge6 and in related alloys Dy(Mn6Ge6)1-x(Fe6Al6)x

• Published in: Journal of alloys and compounds Vol. 423; no. 1-2; pp. 232 - 235
• Main Authors: KERSCHL, Peter, KOZLOVA, Nadezda V, SNIADECKI, Zbigniew, NENKOV, Konstantin, RÖSSLER, Ulrich K, IDZIKOWSKI, Bogdan, MÜLLER, Karl-Hartmut, SCHULTZ, Ludwig
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Lausanne Elsevier 26-10-2006
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic conduction in metals and alloys; Electronic transport in condensed matter; Exact sciences and technology; Galvanomagnetic and other magnetotransport effects; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Physics; Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.); Negative magnetoresistance; Rare-earth intermetallic compound; Electrical conductivity; Helimagnetism; Magnetization; Magnetic ordering; Spin flop; Magnetic transitions; HfFe6Ge6-type structure; Metamagnetism; Hexagonal lattices; DyMn6Ge6; Chemical composition; Magnetoresistance; High-field magnetization measurements; Spin state
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2006.01.096

Magnetoresistance and magnetization measurements on pure DyMn6Ge6 and low-doped Dy(Mn6Ge6)1-x(Fe6Al6)x samples x < or = 0.05 with the hexagonal HfFe6Ge6-type structure are used to investigate the connection between magnetoresistance and magnetization processes in these compounds. At room temperature, DyMn6Ge6 shows negative magnetoresistance MR(H), which is related to a transition from a ferromagnetic helix state into a fan state in this compound. Below 100K, positive MR(H) is found with a non-monotonic dependence in fields above 20T. The anomalous behavior of MR(H) is explained by a sequence of transitions from conical helix to conical fan and a field-driven canting in the ferromagnetic Dy-Mn-subunits at higher fields. This transition transforming the ferrimagnetic fan into a ferromagnetic spin-flop state is discernible as a macroscopic metamagnetic behavior in the magnetization curves. For low substituted samples an increase of the specific resistivity and reduced magnetic ordering temperatures are found. Their MR(H) at high temperatures displays a similar negative behavior as the pure compound. The anomalous low-temperature magnetoresistance behavior is absent in the alloyed samples.