Charge ordering correlated ultrasonic anomalies in La1/3Sr2/3Fe1−xCrxO3 perovskites

Variation of ultrasonic behaviors in R 1/3 Sr 2/3 FeO 3 (R=La, Pr, Gd)

“…The V shows an obvious softening in R = La, while only a slope change was observed in R = Pr. The similar phenomenon was observed in La 1/3 Sr 2/3 Fe 1−x Co x O 3 [22]. It is found that the softening in V below T CO weakens with the Co doping due to the fact that the Co doping makes the Fe 5+ unstable.…”

Effect of Ba-site substitution by Sr on ultrasonic velocity and electron–phonon coupling constant of DyBa2−xSrxCu3O7−δ superconductors

“…Interestingly, the possibility of lattice contribution to the electron pairing mechanism has been supported by a number of experimental evidences [6,7]. The ultrasonic method, which is sensitive to lattice instabilities and phase transitions, was found to be very useful to probe bulk property changes of ceramic materials such as glasses [8][9][10][11], magnetoresistance materials [12][13][14][15], and also high-temperature superconductors [16-24 and references therein]. In the latter, step-like velocity anomalies above 200 K indicating sudden or unexpected elastic hardening taking place in superconducting samples have been observed in several RE123 [16,17], RE1113 [20] and Bi-based samples [18,21].…”

Charge ordering analysis by electrical and dielectric measurements in Ca2−xPrxMnO4 (x=0–0.2) compounds

“…The CO state is related to the weakening of double-exchange (DE) mechanism within ferromagnetic (FM) clusters, explained by the interruption of Mn 3+ -O-Mn 4+ bond [2]. The CO property is not only limited to manganites [9,10]; but also other materials exhibit this property as well, as observed in NdBaFe 2 O 5 [11] and La 1/3 Sr 2/3 Fe 1−x Cr x O 3 [12] compounds. Moreover, it has been discovered that the CO process is accompanied by an increase of the dielectric properties [13,14] and is particularly reported that Pr 0.65 Ca 0.28 Sr 0.07 MnO 3 single crystal has high capacitive behavior just below T CO = 250 K (T CO : CO temperature) [15].…”