Spin waves in ferromagnets and antiferromagnets. I

Frustrated magnetic structure of TmAgGe

“…The spin-wave theory of antiferromagnetic magnons (AFM) with linear dispersion relation e 2 ðkÞ ¼ D 2 þ Dk 2 , where D denotes an energy gap, predicts the following temperature dependence of the magnetic susceptibility [11] w ¼ 1…”

Magnetic, electrical and thermal properties of Tm3Cu4Si4

“…, in which the first two terms represent the nuclear and electronic contributions, respectively, whereas the last one accounts for the antiferromagnetic spinwaves contribution with an energy gap due to uniaxial anisotropy [7] (here, it was assumed that in the temperature range considered the phonon contribution is negligibly small). The least-squares fitting of this formula to the experimental data of Tm 3 Cu 4 Si 4 yielded the parameters: a % 38.1(9) (mJ K)/mol, c % 330(5) mJ/(mol K 2 ), a = 603(4) J/(mol K 3/2 ) and D = 7.8(2) K. The so-derived magnon excitations energy scale D is typical for Tm-based intermetallics [8], yet distinctly smaller than that determined e.g.…”

Magnetic ordering and low-temperature thermodynamic properties of ErFe2Ge2

“…According to the spin-wave theory of antiferromagnetic magnons with the dispersion relation e 2 (k)¼D+Dk 2 , where D denotes an energy gap in the magnon spectrum and D is a stiffness constant. The theory predicts that the magnon contribution to specific heat can be expressed as [7] …”