Enhancement of electromagnetic fields with subwavelength microwave resonators

Probing the band structure of LaTe2 using angle resolved photoemission spectroscopy

“…In panel b, we show data taken with a different polarization vector, along the Γ-M direction (see inset), at 110eV photon energy. We observe that when the photon energy is tuned close to the La and Te adsorption edges (La 4d 3/2 ≈105eV, Te 4p 3/2 ≈103.3eV) we can resolve, although still weak, the inner diamond at the Γ point, predicted by LDA but not observed before [7] within this energy range. We note, however, that despite our extensive search over a wide range of photon energies (between 80 and 200eV) and different polarization conditions, we were unable to resolve the electron pocket centered at the Γ point.…”

“…The existence of a CDW phase in the ditellurides has been first established by transmission electron microscopy (TEM) [7,8] and single crystal X-ray diffraction [9] experiments. TEM measurements have reported a long range distortion q = .5a * [8] similar to the diselenides [10], while single crystal X-ray diffraction expanded on this suggesting a larger 2 × 2 × 1 superstructure [9].…”

“…TEM measurements have reported a long range distortion q = .5a * [8] similar to the diselenides [10], while single crystal X-ray diffraction expanded on this suggesting a larger 2 × 2 × 1 superstructure [9]. Most recently, the TEM work of Shin et al demonstrated a four-fold symmetric superstructure with a modified q=.484a * and proposed an additional CDW wave vector q=.6a * +.2b * [7].…”

“…ARPES is well qualified for studying such materials as it has already proved itself in the study of SmTe 3 [11] and CeTe 3 [12], given their quasi-2D structure. Yet, only quite recently has ARPES been used to study rare earth ditellurides such as LaTe 2 [7]. CDW physics can manifest itself in ARPES data in at least three ways: 1) Observing FS band structure which can be connected or "nested" by a q CDW 2) Gapping of near E F band structure, which represents the energy gained by the instability 3) The appearance of "shadow bands" where the action of the CDW creates new states by shifting the main band structure by q CDW .…”

“…samples were cleaved in situ with a base pressure better than 7 × 10 −11 torr at low temperatures. Recently the question has arisen about whether the differences in sample preparation may be responsible for differences observed in the superstructure by XRD and TEM [7]. The samples used for this study were grown using two different techniques: 1)Mineralization of a stoichiometric binary mixture of elements [14] and 2)A high-temperature Bridgeman method explained by Kwon et al [15].…”