Influence of hydrogenation on the magnetic properties of Er₂Ni₂Al

Chem. Met. Alloys 9 (2016) 169-173

https://doi.org/10.30970/cma9.0350

Khrystyna MILIYANCHUK, Silvie MASKOVA, Ladislav HAVELA, Roman GLADYSHEVSKII

The magnetic properties of Er₂Ni₂Al and Er₂Ni₂AlH_5.3 have been studied in the temperature range 1.5-300 K. Er₂Ni₂Al is an antiferromagnet with T_N = 5 K, as indicated by a pronounced maximum in the temperature dependence of the magnetic susceptibility in magnetic fields below 1 T. In the paramagnetic region, the susceptibility is described by the Curie-Weiss law, yielding an effective moment of 9.69 µ_B/Er and θ_p = ‑14 K. The field dependence of the magnetization in the ordered state exhibits a metamagnetic transition around 2 T with a relatively wide hysteresis. The hydride Er₂Ni₂AlH_5.3 does not show any magnetic ordering above T = 2 K. The Curie-Weiss law fit of the magnetic susceptibility curve yields the values 9.63 µ_B/Er and θ_p = ‑10 K. The magnetic behavior of both Er₂Ni₂Al and Er₂Ni₂AlH_5.3 is supported by the shape of the temperature dependence of the heat capacity curves. The upturn in C/T vs. T for Er₂Ni₂AlH_5.3, which is suppressed by an applied magnetic field, is suggestive of magnetic ordering at still lower temperatures. The dramatic suppression of Er–Er exchange interactions (the size of the Er moments is generally stable) can be understood as a consequence of H bonding, which reduces the concentration of conduction electrons.

Magnetization curves for Er₂Ni₂Al and Er₂Ni₂AlH_5.3.

Keywords

Intermetallic / Hydride / Magnetic properties / Heat capacity