Wave-vector-dependent exchange splitting in a local moment system

Abstract

The electronic structure of strained thin films of Gd has been studied with spin-and angle-resolved photoemission and spin-polarized inverse photoemission. The spin-dependent electronic structure is dominated by a very distinct k dependence of the exchange splitting. The surface magnetic structure is observed to be different from that of the bulk, as indicated by the different electronic structure and a much higher surface Curie temperature. The 4% strain within the Gd films results in an enhanced Curie temperature.

The interplay between the surface band structure and possible surface reconstructions of Mo(112)

“…The IPES system, with a resolution of 420 meV, incorporates an Erdman-Zipf electron gun [23] along with a Geiger-Müller detector with a SrF 2 window in an apparatus previously described elsewhere [24]. The electron energy was swept from 5.5 to 12.5 eV, at incident angles between normal and 60 degrees, or from zone center (Γ ) out to the Brillouin zone edge (Χ ).…”

Band structure of strained Gd(0001) films

“…With this aim, we perform a detailed comparison of theoretical surface and bulk band structures, with experimental data obtained by spin-polarized photoemission ͑SPES͒ and spin-polarized inverse photoemission ͑SPIPES͒ ͑partly published elsewhere 8,29 ͒. The band structures have been calculated by the linear augmented-plane-wave ͑LAPW͒ method for thin films.…”

“…21 The expansive 4% in-plane strained Gd͑0001͒ on Mo͑112͒ results in a quite different electronic structure and altered magnetic properties compared to the strain relieved Gd͑0001͒ grown on W͑110͒, 27 as noted elsewhere. 8,21,28,29 Based on studies of rare-earth alloys, Andrianov 19,20 suggested that the Fermi surface is sensitive to both composition and lattice deformation. It was shown 28 that the relief of the strain in Gd͑0001͒ on Mo͑112͒ with increasing film thickness results in a spin-polarized electronic structure that is increasingly similar to the largely unstrained Gd͑0001͒ films grown on W͑110͒.…”

“…[3][4][5][6] Compression of gadolinium is seen to lead to a suppression of T c , 3,6 while expansion leads to an increase of T c . 7,8 Not only does strain affect the magnetic properties, as now detailed fairly extensively for the perovskites, [9][10][11][12][13][14][15][16][17] but it has long been established that the lattice constant has a profound influence on the electronic structure, 18 -20 even for the thinnest of thin films. [21][22][23][24][25][26] Gd͑0001͒ grown on Mo͑112͒ exhibits a substantial inplane expansive strain compared to a similar thickness of Gd͑0001͒ on W͑110͒.…”

“…27͒ should be applicable to Gd͑0001͒ on Mo͑112͒. 28 While a number of experimental studies have been undertaken to investigate the spin-polarized band structure of strained Gd͑0001͒, 7,8,29 an interpretation of experimental data is complicated by the close proximity of bulk and surface bands, and the large number of observed unoccupied bands, not seen with Gd͑0001͒ on W͑110͒. [30][31][32] A great interest in the behavior of the surface and bulk band structure of gadolinium has provoked a number of theoretical investigations of the Gd͑0001͒ surface using various calculational techniques and approximations for exchange-correlation potential.…”