We present specific heat and ultrasonic measurements on the rare earth tritelluride ErTe3 compound. Thermodynamic anomalies are observed at the upper charge density wave (CDW) phase transition ...TCDW1=265K and the second one at TCDW2=155K. Similar critical behaviors are found at both CDW phase transitions and that we tentatively described in terms of the 3D XY model. Different anisotropic stress dependences ∂TCDW1/∂σii and ∂TCDW2/∂σii are found at the two successive CDW phase transitions. Magnitude of the elastic constant anomalies at TCDW2 is ten times smaller than that at TCDW1. Anomalies in the elastic constants at the upper CDW TCDW1 exhibit two dimensional features in the layer planes while in contrast a three dimensional behavior is observed at TCDW2.
Measurements of the real R and imaginary X parts of the surface impedance were performed in underdoped BaFe1.93Ni0.07 As2 crystals in the frequency range 10MHz–1.5GHz. The establishment of the ...antiferromagnetic order at TN~50K gives rise to anomalous increase of electron scattering time. Drude type conductivity yields X and R differ from each other. The increase of the real conductivity σ1 in the superconducting state is attributed to a rapid decrease of the quasiparticle scattering time. This result gives evidence of coexistence of superconductivity and antiferromagnetism.
•Surface impedance measurements of superconducting underdoped BaFe1.93Ni0.07As2 crystals.•Real R and imaginary X parts of the surface impedance differ from each other in the antiferromagnetic state.•Effective conductivity in the superconducting state is extracted.
Measurements of the real σ1 and imaginary σ2 part of the conductivity were performed in optimally doped BaFe1.9Ni0.1As2 and overdoped BaFe1.88Ni0.12As2 crystals in the frequency range 20MHz–1.5GHz ...using a single coil technique. The temperature dependence of the London penetration depth follows a T2 law. The conductivity σ1 increases with decreasing temperature below Tc in agreement with the results obtained for the optimally Co doped BaFe2−xCoxAs2 crystals. The increase of σ1 in the superconducting state is attributed to a rapidly decrease of the quasiparticle scattering rate.
•Surface impedance measurements on superconducting BaFe2−xNixAs2 crystals are reported.•Real part of the conductivity increases below the superconducting transition.•Determination of the quasiparticle scattering time.
Ultrasonic measurements on a single crystal of the intermetallic compound Lu5Ir4Si10 are presented. Large anomalies in the velocity and ultrasonic attenuation of the elastic modes are observed at the ...structural phase transition TS∼80 K. The velocity of the longitudinal C11 and C33 mode exhibits a second order transition behavior. In contrast the velocities of the shear C44 and C66 modes exhibit a first order transition behavior. The longitudinal C11 mode is strongly coupled to the ordering system below TS. Similarities in the longitudinal elastic anomalies with known reduced dimensional charge density wave systems suggest that the nature of the structural phase transition TS in Lu5Ir4Si10 could be associated with a charge density wave phase transition.
•Charge density wave phase transition.•First order phase transition.•Elastic constants.
The set of elastic constants of the charge density wave (CDW) rare earth tritelluride TbTe3 has been measured at 15MHz in the temperature range 300–360K. Large anomalies in the velocity and ...ultrasonic attenuation of the longitudinal C11 and C33 modes are observed at the charge density wave phase transition TCDW=333K. Anisotropic stress dependence ∂TCDW/∂σ is found, the components ∂TCDW/∂σ11 and ∂TCDW/∂σ33 in the (a,c) plane are one order of magnitude larger than the component ∂TCDW/∂σ22 perpendicular to it. The Landau theory has been used to explain the experimental data. Critical behaviour near the charge density wave phase transition is described in terms of a phenomenological dynamic scaling theory.
•Set of elastic constants of rare earth tritelluride TbTe3 crystals are reported.•Large anomalies in the velocity and ultrasonic attenuation at the charge density wave phase transition.•Critical behaviour is analyzed.
We report sound velocity and ultrasonic attenuation measurements in the vicinity of the successive magnetic phase transitions Tmag1~6.5K, Tmag2~5.8K and Tmag3~5.3K in the charge density wave TbTe3 ...compound. A detailed investigation of the critical contributions to the temperature dependences of the sound velocity and ultrasonic attenuation is presented. Anisotropic stress dependences ∂Tmag1/∂σ found at the antiferromagnetic phase transition Tmag1 is associated with the layered structure of this compound. An abrupt step-like increase in the velocity and a sharp peak in the attenuation are observed with the longitudinal and shear modes at the lock-in magnetic phase transition Tmag3=5.3K. The critical velocity and attenuation behaviors in the high temperature paramagnetic above Tmag1 are described in terms of a phenomenological dynamic scaling expression.
•Large anomalies in the velocity and ultrasonic attenuation at the magnetic phase transitions of TbTe3.•Critical behavior is analyzed.
Anomalies found in the electronic conductivity and the elastic constants C33 and C44 around the superconducting phase transition in the underdoped BaFe1.93Ni0.07As2 compounds are re-examined. The ...large anomalies in the elastic constants C33 and C44 modes and the unusual temperature dependence of the real part σ1 of the electronic conductivity found around the superconducting phase transition TC ~ 16K are attributed to magnetic fluctuations. The establishment of a magnetic order at TM ~ 21K results in a marked decrease of the scattering of electronic carriers.
•Surface impedance results of BaFe2−xNixAs2 crystals are re-examined.•Increase of the real part of the conductivity found around the superconducting phase transition.•Superconductivity and magnetic fluctuations.
We present specific heat and ultrasonic measurements on the rare earth tritelluride ErTe3 compound. Thermodynamic anomalies are observed at the upper charge density wave (CDW) phase transition ...TCDW1=265 K and the second one at TCDW2=155 K. Similar critical behaviors are found at both CDW phase transitions and that we tentatively described in terms of the 3D XY model. Different anisotropic stress dependences ... and ... are found at the two successive CDW phase transitions. Magnitude of the elastic constant anomalies at TCDW2 is ten times smaller than that at TCDW1. Anomalies in the elastic constants at the upper CDW TCDW1 exhibit two dimensional features in the layer planes while in contrast a three dimensional behavior is observed at TCDW2.
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