Physica C: Superconductivity and its Applications, 295(1-2):22-38, 1998. cited By 8Paper doi abstract bibtex
We report a study of the second order dynamic susceptibility in parallel static and alternating magnetic fields of three lightly oxygenated single crystals of La2CuO4+x (x < 0.03) with different TN (TN1 ≈ 222 K, TN2 ≈ 272 K and TN3 ≈ 243 K). The response of all the samples reveals common features which are characteristic of an antiferromagnet with a weak ferromagnetism (WF). These new magnetic properties are attributed to the oxygen-rich phase forming in the course of the phase separation. We show that the WF can be related to out-of CuO2 plane ordering (staging) of the interstitial oxygen. The response of crystals N1 and N3 is observed in the vicinity of TN and exhibits a critical enhancement. A simple model of WF domain is presented which allows us to describe quantitatively the H-dependence of the signal of crystal N3 above TN. It provides a basis for a comparative analysis of the data on N1 and N3 crystals. The response of crystal N2 is found below TN. In this case its peculiarities reflect change and destruction of initial magnetic ordering in the forming oxygen-rich phase. © 1998 Elsevier Science B.V.