An absolute capacitance dilatometer

Stability of antiferromagnetism at high magnetic fields inMn3Si

“…Measurements of ρ(T ) as function of pressure show that T N increases as dT N /dp ≈ 0.4 K/kbar, in agreement with the Ehrenfest relation [9,15] and many other Heusler compounds [24]. This contrasts the majority of weakly magnetic transition metal, actinide and lanthanide compounds [23].…”

“…The T 3 dependence of C(T ) may not be accounted for by lattice contributions, which are negligibly small up to 30 K as estimated from the Debye temperature Θ D = 454 K, where β D ≈ 2.1 · 10 −5 J/molK 4 [15]. More surprisingly, an estimated contribution of localmoment antiferromagnetic spin waves to C(T ) given by…”

“…The T 3 dependence of C(T ) may not be accounted for by lattice contributions, which are negligibly small up to 30 K as estimated from the Debye temperature Θ D = 454 K, where β D ≈ 2.1 • 10 −5 J/molK 4 [15]. More surprisingly, an estimated contribution of localmoment antiferromagnetic spin waves to C(T ) given by ∆C sw (T ) = β sw T 3 (β sw ≈ 1.65 • 10 −5 J/mol K 4 ) is two orders of magnitude smaller than experiment, where a conservative estimate of an average J ≈ 1.9 meV, derived from the experimentally measured low-T spin-wave velocity c l [12,16], corresponds to a mean field ordering temperature T N ≈ 30 K, in broad quantitative agreement with experiment.…”