TY - JOUR
T1 - Quantum and thermal ionic motion, oxygen isotope effect, and superexchange distribution in La2CuO4
AU - Haefliger, P. S.
AU - Gerber, S.
AU - Pramod, R.
AU - Schnells, V. I.
AU - dalla Piazza, B.
AU - Chati, R.
AU - Pomjakushin, V.
AU - Conder, K.
AU - Pomjakushina, E.
AU - Le Dreau, L.
AU - Christensen, Niels Bech
AU - Syljuasen, O. F.
AU - Normand, B.
AU - Rønnow, Henrik Moodysson
PY - 2014
Y1 - 2014
N2 - We study the zero-point and thermal ionic motion in La2CuO4 by means of high-resolution neutron-diffraction experiments. Our results demonstrate anisotropic motion of O and, to a lesser extent, Cu ions, both consistent with the structure of coupled CuO6 octahedra, and quantify the relative effects of zero-point and thermal contributions to ionic motion. By substitution of O-18, we find that the oxygen isotope effect on the lattice dimensions is small and negative (-0.01%), while the isotope effect on the ionic displacement parameters is significant (-6 to 50%). We use our results as input for theoretical estimates of the distribution of magnetic interaction parameters, J, in an effective one-band model for the cuprate plane. We find that ionic motion causes only small (1%) effects on the average value , which vary with temperature and O isotope, but results in dramatic (10-20%) fluctuations in J values that are subject to significant (8-12%) isotope effects. We demonstrate that this motional broadening of J can have substantial effects on certain electronic and magnetic properties in cuprates.
AB - We study the zero-point and thermal ionic motion in La2CuO4 by means of high-resolution neutron-diffraction experiments. Our results demonstrate anisotropic motion of O and, to a lesser extent, Cu ions, both consistent with the structure of coupled CuO6 octahedra, and quantify the relative effects of zero-point and thermal contributions to ionic motion. By substitution of O-18, we find that the oxygen isotope effect on the lattice dimensions is small and negative (-0.01%), while the isotope effect on the ionic displacement parameters is significant (-6 to 50%). We use our results as input for theoretical estimates of the distribution of magnetic interaction parameters, J, in an effective one-band model for the cuprate plane. We find that ionic motion causes only small (1%) effects on the average value , which vary with temperature and O isotope, but results in dramatic (10-20%) fluctuations in J values that are subject to significant (8-12%) isotope effects. We demonstrate that this motional broadening of J can have substantial effects on certain electronic and magnetic properties in cuprates.
U2 - 10.1103/PhysRevB.89.085113
DO - 10.1103/PhysRevB.89.085113
M3 - Journal article
SN - 0163-1829
VL - 89
JO - Physical Review B Condensed Matter
JF - Physical Review B Condensed Matter
IS - 8
M1 - 085113
ER -