Casalta, H.; Schleger, P.; Brecht, E.; Montfrooij, W.; Andersen, N. H.; Lebech, B.; Schmahl, Wolfgang W.; Fuess, H.; Liang, R.; Hardy, W.N.; Wolf, Th.
Absence of a second antiferromagnetic transition in pure YBa2Cu3O6+x.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 50, No. 13: pp. 9688-9691
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Magnetic ordering has been investigated by means of neutron scattering in an YBa2Cu3O6+x single crystal prepared with two different oxygen concentrations, x=0.1 and x=0.18, and in an aluminum-doped YBa2(Cu3-yAly)O6+x crystal with x=0.25 and y=0.14. For the undoped crystal, a magnetic ordering transition was observed at TN=410 (respectively for x=0.1 and x=0.18), but no second magnetic transition was found down to 2 K. In contrast, an antiferromagnetic reordering was observed for the aluminum-doped sample with a transition temperature T2=8 K. This implies a high sensitivity of this second phase to impurities and indicates that the transition is not necessarily an intrinsic property of YBa2Cu3O6+x.