Lattice dynamics ofLa2NiO4

Temperature dependence of the electronic structure of theJeff=12Mott insulatorMoon1, Jin2, Choi3 et al. 2009Phys. Rev. B157251005View full textAdd to dashboardCite

“…Figure 4͑d͒ shows the phonon frequency ph of each mode normalized to ph ͑10 K͒. While the ph of the other phonon modes changes less than 1%, that of the higher-frequency bending mode, which is related to the modulation of the in-plane bond angle, 28 changes by about 3%. ͑The change in the ph is about 1 cm −1 for the external and lower-frequency bending modes and 3 cm −1 for the stretching mode, respectively.…”

“…The phonon modes are classified into three groups: external, bending, and stretching modes. 28,29 Figures 4͑a͒-4͑c͒ show the external, bending, and stretching modes, respectively. While the external mode is related to the vibrations of the Sr ions against IrO 6 octahedra, the bending and stretching modes are related to the modulation of the Ir-O-Ir bond angle and the Ir-O bond length, respectively.…”

In-plane and out-of-plane plasma resonances in optimally doped La1.84Sr0.16CuO4

“…In addition, there exists a small dip at ~ 92 cm -1 in the reflectivity of P-LSCO even at room temperature as also indicated with a red arrow. (2), and A 2u (1) modes [24] survive the screening, and appear respectively at C 1 ~ 220 cm -1 , C 2 ~ 350 cm -1 , and C 3 ~ 500 cm -1 in the P-LSCO plot. On the contrary, all three E u modes of the ab-plane [24] are screened out upon doping and the new ab-plane doping-induced modes indicated as X 1 and X 2 appear instead as a result of the symmetry breaking of the Raman-active E 1g (2) and E 1g (1) ab-plane modes respectively [25,26].…”

“…(2), and A 2u (1) modes [24] survive the screening, and appear respectively at C 1 ~ 220 cm -1 , C 2 ~ 350 cm -1 , and C 3 ~ 500 cm -1 in the P-LSCO plot. On the contrary, all three E u modes of the ab-plane [24] are screened out upon doping and the new ab-plane doping-induced modes indicated as X 1 and X 2 appear instead as a result of the symmetry breaking of the Raman-active E 1g (2) and E 1g (1) ab-plane modes respectively [25,26]. However the additional ab-plane dopinginduced modes ω G1 ~ 23 cm -1 , ω G2 ~ 36 cm -1 , and ω G3 ~ 72 cm -1 do not have their counterparts in the Raman spectra of the CuO 2 lattice as pointed out in Ref [26,27].…”

Low temperature anomaly of LO phonons in La[sub 1.85]Sr[sub 0.15]CuO[sub 4] and YBa[sub 2]Cu[sub 3]O[sub 7]

“…One is the apparent large discontinuity of dispersion around (0.25, 0, 0) at 10 K, and the other is the strong temperature dependence. The apparent discontinuity in dispersion was observed also for B~.sKo.4BiOs [6], nickelate [7] and more recently in doped CMR manganite [8]. Since the softening of the oxygen LO phonons at the zone edge is clearly related to the presence of the doped holes [5,9,10], it may be argued that the discontinuity at (0.25, 0, 0) must also be intimately connected with the presence of charges.…”