| SM ISO690:2012|
SEIDOV, Z.; GUNTHER, A.; FILIPPOVA, Irina; KRUG VON NIDDA, Hans Albrecht; TSURKAN, Vladimir; LOIDL, Alois. Magnetic properties of the covalent chain antiferromagnets RbFeSe2 and TlFeX2 (X=S, Se). In: Materials Science and Condensed Matter Physics. Editia a 7-a, 16-19 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, p. 124.
|Materials Science and Condensed Matter Physics
Editia a 7-a, 2014
Conferința "Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 16-19 septembrie 2014
Single crystals of the temruy iron chalcogenides RbFeSe2, T1FeS2, and T1FeSe2 have been investigated by means of X-ray diffraction, magnetic susceptibility, magnetization, specific heat, and electron-spin resonance (ESR) measurements. The crystal strncture of RbFeSe2 is shown in Fig. 1. The FeSe4 tetrahedra build infinite chains along the c-direction and are separnted by the Rb alkali atoms. All three compounds exhibit three-dimensional collinear antife1rnmagnetic order with strongly reduced moments below T r248 K, 196 K, and 290 K, respectively. The magnetic moments ru·e oriented perpendicular to the chain direction. The specific heat measurements ofT1FeX2 (X=S, Se) do not show any anomaly at TN [l]. The specific heat of RbFeSe2 was measured by a relaxation method using a PPMS Quantum Design in the temperature range 1.8 K :ST :S 300 K and in magnetic fields up to 90 kOe. The magnetic field was applied perpendicular to the chain direction. Fig. 2 shows the specific heat C(l) as function of temperature for RbFeSe2. The temperature (TN = 248K) at which a small A-like anomaly is obse1ved in the C(T) data is the same at which a discontinuity in the slope in the temperature dependence of the magnetic susceptibility x(l) was found. However, the calculated entropy for RbFeSe2 is much smaller than expected for a low-spin S=1/2 Fe3+ system. The linear increase of the paramagnetic susceptibility and ESR intensity of RbFeSe2 and TlFeX2 (X=S, Se) strongly suggests a one-dimensional metallic character at high temperatures. This is an evidence of a long-range AFM order.