Direct observation of a coupling between spin, lattice and electric dipole moment in multiferroicYMnO3

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO3

“…This can be written as [48] Figure 7. (a) Original low temperature lattice parameter data from Lee et al [35] (blue squares and purple crosses) and high temperature data from Gibbs et al [15] (green squares and red crosses including scaled low temperature data to allow fitting over the entire temperature range). High temperature fit coefficients (fits made above 1320 K) for a: a 1 = 6.157Å, a 2 = 8.492 × 10 −5Å , θ s set at 141 K, c: c 0 = 11.34-3.014 × 10 −5 T and for cell volume (not shown): a 1 = 370.0Å 3 , a 2 = 0.0122Å 3 , θ s set at 141 K. (b) Strains e 1 , e 3 and e v as a function of temperature.…”

“…The curved solid line is a Landau 246 fit to e 3 high temperature data. (c) Low temperature strains alone, calculated from lattice parameter data from [35] ( figure 7(a)). Fit coefficients for a: a 1 = 6.10Å, a 2 = 8.86 × 10 −5Å , θ s = 141 K, c: a 1 = 11.42Å, a 2 = −7.63 × 10 −5Å , θ s set at 141 K and cell volume: a 1 = 369Å 3 , a 2 = 0.0084Å 3 , θ s set at 141 K.…”

“…Lattice parameter data from Lee et al [35] and Gibbs et al [15] are used here to characterize spontaneous strains arising at both the magnetic ordering transition and the high temperature structural transition. The primary lattice parameter data are reproduced in figure 7(a) with the low temperature data scaled to overlap with the high temperature data.…”

“…Mn(x) position [38] 0.324 72 [15] 0.317 7(9) [35] 0.333 0(17) [29] 0.320 8(18) [39] (at 10 K) 0.333 5 (6) largest amount of stiffening was observed for C 66 (∼3%) and C 11 (∼1%), in comparison with C 33 and C 44 (<0.1%), corresponding to a stronger influence of magnetic interactions directed within the (001) plane rather than perpendicular to it. Using a Landau description the relevant strain/order parameter coupling term was determined to be λe 2 S 2 ⊥ , where e is a strain, λ is a strain/order parameter coupling constant, and S ⊥ is the in-plane spin component representing the magnetic order parameter.…”

“…The magnetoelastic coupling effect in YMnO 3 has been the subject of much work in recent years and a series of neutron diffraction experiments has been carried out to monitor changes in lattice parameters and atomic positions at T N [7,10,29,[35][36][37]. Monitoring of changes in atomic positions and bond lengths is difficult due to the small changes involved.…”