title: Anisotropy of magnetic properties of Fe(1+y)Te.
abstract: The magnetic properties of Fe(1+y)Te single crystals (y ≃ 0.1 ÷ 0.18) were studied at temperatures 4.2 ÷ 300 K. At an ambient pressure, with decreasing temperature a drastic drop in χ(T) was confirmed at T ≃ 60 ÷ 65 K, which appears to be closely related to the antiferromagnetic (AFM) ordering. It is found that the magnitudes of the anisotropy of magnetic susceptibility Δχ in the AFM phase are close in the studied samples, whereas the sign of the anisotropy apparently depends on the small variations of the excess iron y in Fe(1+y)Te samples. The performed DFT calculations of the electronic structure and magnetic properties for the stoichiometric FeTe compound indicate the presence of frustrated AFM ground states. There are very close energies and magnetic moments for the double stripe configurations, with the AFM axes oriented either on the basal plane or along the [0 0 1] direction. Presumably, both these configurations can be realized in Fe(1+y)Te single crystals, depending on the variations of the excess iron. This can provide different signs of magnetic anisotropy in the AFM phase, presently observed in the Fe(1+y)Te samples. For these types of AFM configuration, the calculations for the FeTe values of Δχ are consistent with our experimental data.
authors.affiliation: B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkov, Ukraine.
authors.forename: G E
authors.initials: GE
authors.lastname: Grechnev
authors.forename: A S
authors.initials: AS
authors.lastname: Panfilov
authors.forename: A V
authors.initials: AV
authors.lastname: Fedorchenko
authors.forename: A A
authors.initials: AA
authors.lastname: Lyogenkaya
authors.forename: I P
authors.initials: IP
authors.lastname: Zhuravleva
authors.forename: D A
authors.initials: DA
authors.lastname: Chareev
authors.forename: A N
authors.initials: AN
authors.lastname: Nekrasov
authors.forename: E S
authors.initials: ES
authors.lastname: Mitrofanova
authors.forename: O S
authors.initials: OS
authors.lastname: Volkova
authors.forename: A N
authors.initials: AN
authors.lastname: Vasiliev
authors.forename: O
authors.initials: O
authors.lastname: Eriksson