Spontaneous ferromagnetic spin ordering at the surface of La${}_2$CuO${}_4$

Abstract

Magnetic properties of high purity stoichiometric La${}_2$CuO${}_4$ nanoparticles are systematically investigated as a function of particle size. Ferromagnetic single-domain spin clusters are shown to spontaneously form at the surface of fine grains as well as paramagnetic defects. Hysteresis loops and thermomagnetic irreversibility are observed in a wide temperature range $5-350$ K with the remnant moment and coercivity gradually decreasing with increasing temperature. Possible origins of the spontaneous surface ferromagnetic clusters and the relation of our data to the appearance of unusual magnetic phenomena and phase separation of doped cuprates are discussed.

10 pages, 15 figures

References in corpus (4)

• Unusual magnetic susceptibility anisotropy in untwinned La_{2-x}Sr_xCuO_4 single crystals in the lightly-doped region
• Magnetic order in the normal state of the archetypal high-Tc superconductor La2-xSrxCuO4
• Decomposition of the spin-1/2 Heisenberg chain compound Sr2CuO3 in air and water: An EPR and magnetic susceptibility study of Sr2Cu(OH)6
• Thermo-magnetic hysteretic properties resembling superconductivity in the normal state of La1.85Sr0.15CuO4