Magnetoelastic effect in <i>R</i> ₅ Pt ₂ In ₄ ( <i>R</i> = Tb–Tm) investigated by neutron powder diffraction

Thermal evolution of the unit-cell parameters a, b and c as well as the unit-cell volume V of R₅Pt₂In₄ (R = Tb-Tm) is derived from the neutron powder diffraction data. For all investigated compounds, the above mentioned parameters show a noticeable change in vicinity of the critical temperature of the magnetic order. At lower temperatures, additional anomalies are found for R = Tb-Er. These anomalies are related to the magnetic phase transitions of the order-order type originating from appearance and/or rapid increase of the magnetic rare earth moment at one of the 4g Wyckoff sites. The above mentioned results indicate presence of the magnetoelastic effect in the investigated intermetallics. Based on the experimental data, the product of compressibility and magnetoelastic coupling in R₅Pt₂In₄ (R = Tb-Tm) is found to be 0.014 (2)%·μ_B^-2.