Anisotropic Spin-Fluctuations in SmCoPO Revealed by P-31 NMR Measurement

P-31 NMR spectral features in polycrystalline SmCoPO reveal an axially symmetric local magnetic field. At low temperature, the anisotropy of the internal magnetic field increases rapidly, with K-ab increasing faster than that of K-c. The dominant contribution to this anisotropy arises from Sm-4f electron contribution over that of Co-3d. The intrinsic width 2 beta deviates from linearity with respect to bulk susceptibility below 170 K due to the enhancement of (1/T-2)(dynamic), which along with the continuous increase of anisotropy in the internal magnetic field is responsible for the wipe out effect of the NMR signal, well above T-C. 1/T-1 shows large anisotropy confirming a significant contribution of Sm-4f electron spin fluctuations to 1/T-1, arising from indirect RKKY type exchange interaction indicating a non-negligible hybridization between Sm-4f orbitals and the conduction band, over the itinerant character of the Co-3d spins. This anisotropy originates from the orientation dependence of chi ''(q, omega). The 3d-spin fluctuations in the ab-plane is 2D FM in nature, while along the c-axis, a signature of a weak AFM spin fluctuations superimposed on weak FM spin-fluctuations even in a field of 7 T and far above T-N is observed. The enhancement of this AFM fluctuations of the Co-3d spins along c-axis, at further low temperature is responsible to drive the system to an AFM ordered state

Magnetotransport Irreversibility in Single Crystalline La0.18Pr0.40Ca0.42MnO3 Thin Films

Magnetotransport irreversibility in single crystalline La0.18Pr0.40Ca0.42MnO3 thin films is probed with respect to intrinsic electronic phase separation (IEPS). Temperature-dependent magnetization and resistivity measurements show that (i) the high temperature non-hysteretic regime is dominated by the antiferromagnetic insulator (AFMI) and the charge ordered (CO) phases; (ii) at intermediate temperatures hysteretic regime is akin to a spin liquid; and (iii) the glass transition occurs at temperature T-g below which the spin liquid freezes. The suppression of the ferromagnetic and insulator-metal transitions (T-C and T-IM) during cooling confirms supercooled magnetic liquid. Magnetic field-dependent resistivity (rho-H) measured during cooling and warming highlights the differences in the spin-ordered structures through (i) reversible behavior at T T-IM (warming). The present study demonstrates that the scaling of area between the isothermal cooling and warming cycle rho-H curves with temperature mimics the rho-T behavior and hence also reflects the insulator-metal transition. The observed irreversibility and the area scaling in the different spin regimes have been explained in terms of the intrinsic electronic phase separation