Magnetostriction and magneto-structural domains in antiferromagnetic   YBa$_{2}$Cu$_{3}$O$_{6}$
  We have used high-resolution neutron Larmor diffraction and capacitative dilatometry to investigate spontaneous and forced magnetostriction in undoped, antiferromagnetic YBa$_2$Cu$_3$O$_{6.0}$, the parent compound of a prominent family of high-temperature superconductors. Upon cooling below the N\'eel temperature, $T_N = 420$~K, Larmor diffraction reveals the formation of magneto-structural domains of characteristic size $\sim 240$~nm. In the antiferromagnetic state, dilatometry reveals a minute ($4 \times 10^{-6}$) orthorhombic distortion of the crystal lattice in external magnetic fields. We attribute these observations to exchange striction and spin-orbit coupling induced magnetostriction, respectively, and show that they have an important influence on the thermal and charge transport properties of undoped and lightly doped cuprates. 
B. Nafradi, T. Keller, F. Hardy, C. Meingast, A. Erb, B. Keimer
cond-mat.str-el cond-mat.supr-con