Proximity effect of vanadium on spin-density-wave magnetism in Cr films

Abstract

The spin-density wave (SDW) state in thin chromium films is well known to be strongly affected by proximity effects from neighboring layers. To date the main attention has been given to effects arising from exchange interactions at interfaces. In the present work we report on combined neutron and synchrotron scattering studies of proximity effects in Cr/V films where the boundary condition is due to the hybridization of Cr with paramagnetic V at the interface. We find that the V/Cr interface has a strong and long-range effect on the polarization, period, and the N\'{e}el temperature of the SDW in rather thick Cr films. This unusually strong effect is unexpected and not predicted by theory.Comment: 7 figure

Island-assisted interface alloying and magnetic polarization at submonolayer V/Cr(001) interfaces

“…For these higher coverages, however, the magnetic contrast on both the terraces and the islands starts to vanish. This is consistent with previous studies where the onset of a magnetically dead layer close to the Cr/V interface was observed 9,10,14,15 in thick enough V films. This fact is attributed to the Cr-V interface hybridization, which causes a short-range suppression of the SDW magnetism near the Cr/V interfaces, leading to pinning of SDW nodes at the interfaces, as theoretically predicted.…”

“…The substrate deposition temperature during growth was 525 K, which reportedly leads to abrupt interfaces. 9,10,14,15 In this study, V coverages ranging from 0.12 to 1.65 AL where explored. The SP-STM measurements were performed at 157 K using a STM system attached to the analysis chamber.…”

“…Furthermore, recent neutron-scattering experiments have shown that proximity effects at Cr/V interfaces lead to the appearance of a 50 Å wide magnetically dead Cr layer near the Cr/V interface, the suppression of the spin-flip transition, and the stabilization of a single-domain spin-density wave ͑SDW͒ in Cr with out-of-plane spins and out-of-plane propagation wave vector. 9,15 While the reduction in the Cr magnetic moment has been demonstrated experimentally, the magnetic state of V in contact with antiferromagnetic Cr͑001͒ remains unexplored and unclear. The observation of the V magnetic state at the interface with Cr͑001͒ is challenging since the magnetic moments of adjacent antiparallel layers compensate and cannot be detected with spatially averaging methods.…”

“…By combining scanning tunneling microscopy ͑STM͒ and spectroscopy ͑STS͒ with density-functional theory ͑DFT͒ calculations we show that V growth on Cr͑001͒ at 525 K leads to island-assisted alloying between the substrate and the islands in contrast to the expected formation of a chemically abrupt interface. 9,10,14,15 A radial concentration gradient can be observed during the early stages of growth with a high Cr concentration in the island center and a gradually increasing V concentration toward the island rim. Upon coalescence this gradient across the islands leads to a monolayer with inhomogeneous composition.…”

Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems

“…The extrapolation to Q = 0 suggest a ratio of L /2 S = 0.14 ± 0.08 between orbital angular momentum and spin contributions to the magnetic moment [27]. The non-resonant X-ray scattering regime has also important applications in the domain of spin-density waves [29], charge density waves [30] or surface magnetism that exploits surface refraction effects of the charge scattering, in order to disentangle the magnetic and structural contributions from magnetic surfaces [31].…”