Sabina Ronneteg

TlCu1.73Fe0.27Se2 studied by means of Mössbauer spectroscopy and SQUID magnetometry

TlCu2?xFexSe2 is a p-type metal for x<0.5 which crystallizes in a body-centred tetragonal structure. The metal atoms are situated in ab-planes, ~7?? apart, while the metal?metal distance within the plane is ~2.75??. Due to the large difference in cation distances, the solid solutions show magnetic properties of mainly two-dimensional character. The SQUID measurements performed for x = 0.27 give the c-axis as the easy axis of magnetization, but also show clear hysteresis effects at 10?K, indicating a partly ferromagnetic coupling. The magnetic ordering temperature Tc is 55(5)?K as found from both SQUID and M?ssbauer spectra. At the magnetic hyperfine fields are distributed with a maximum at about 30?T, which are compared to the measured magnetic moment per iron atom, which is 0.97??B/Fe as found from SQUID measurements. The experimental results are compared to results using other methods on isostructural Tl selenides.

Magnetic properties of TlCu2-xFexSe2 crystals

The magnetic properties of two compositions of random solutions in the TlCu2–xFexSe2 system with x=0.2 and 0.45 have been investigated by superconducting quantum interference device magnetometry. T ...

Magnetic Properties of TlCo 2 Se 2 Studied by Mössbauer Spectroscopy

The quasi two-dimensional antiferromagnetic compound TlCo2Se2 has been studied by 57Fe Mossbauer spectroscopy. Small single crystals have been made with 2% Fe doping. The Mossbauer spectrum, developed below the Neel temperature of 85 K, reveals a distribution of magnetic hyperfine fields (MHF). The fit is reasonably good if we suppose a connection between the values and mutual orientation of the EFG and MHF. That allows us to suggest the existence of a modulation in the helical magnetic structure, discovered earlier by neutron diffraction.