Onset of spin-density-wave antiferromagnetism inCr∕Vmultilayers

Abstract

Spin-density-wave ͑SDW͒ magnetism in a series of Cr/ V heterostructures with different Cr thicknesses was systematically investigated by combined resistivity, neutron, and synchrotron scattering measurements. We show that the onset of the bulklike SDW state comes through several necessary steps from a paramagnetic state through a commensurate SDW to an incommensurate SDW. The Néel temperature for the incommensurate SDW is found to scale with Cr thickness and reaches the bulk value at a Cr thickness of about 2000 Å. The proximity effect from Cr/ V interfaces is found to lead to ͑i͒ the appearance of a 50-Å magnetically dead Cr layer near Cr/ V interfaces and ͑ii͒ suppression of the spin-flip transition and stabilization of a single-domain SDW with out-of-plane spins and out-of-plane propagation wave vector. Finally, we show that the SDW period increases with decreasing Cr thickness and becomes temperature independent in sufficiently thin Cr layers.

Tunnel-mediated coupling between antiferromagnetic thin films

“…These would be the signature of a magnetic coupling in our systems, and would be localized near the Cr/MgO interfaces. For Cr(1 1 0) and Cr(0 0 1) surfaces, the magnetic ordering of Cr (anisotropy and phase) can indeed be modified on a significant thickness through interface effects [7,9,36,37]. In our case, the modification of the local magnetic order is more subtle as the incommensurability parameter has an intermediate value δ ≈ δ ≈ 0.035 between that of the top δ = 0 and the bottom δ ≈ 0.047 layer.…”

“…The discovery of giant magnetoresistance in Fe/Cr superlattices [5] triggered an intense research effort on the magnetic properties of Cr thin films [6,7] and multilayers [8][9][10][11][12]. In all these examples, the magnetism remains purely itinerant since all layers are metallic.…”

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

“…6 Of special interest has been the V/Cr͑001͒ interface, which is still controversially discussed and has attracted considerable attention in recent years. [7][8][9][10][11][12][13] Both V and Cr are bcc 3d transition metals with approximately half-band filling. Cr exhibits antiferromagnetism along the ͗001͘ direction such that the ͑001͒ planes couple antiferromagnetically from layer to layer.…”

“…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.…”