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The recent discovery of high-temperature superconductivity in iron-based pnictides (chalcogenides) not only triggers tremendous enthusiasm in searching for new superconducting materials, but also opens a new avenue to the study of the Kondo physics. CeFeAsO is a parent compound of the 1111-type iron-based superconductors. It shows 3d-antiferromagnetic (AFM) ordering below ∼ 139 K and 4f-AFM ordering below ∼ 4 K. On the other hand, the phosphide CeFePO is a ferromagnetically correlated heavy-fermion (HF) metal with Kondo scale TK ∼ 10 K. These properties set up a new platform for research of the interplay among magnetism, Kondo effect, and superconductivity (SC). In this review, we present the recent progress in the study of chemical pressure effect in CeFeAsO1−yFy (y = 0 and 0.05). This P/As-doping in CeFeAsO serves as an effective controlling parameter which leads to two magnetic critical points, xc1 ≃ 0.4 and xc2 ≃ 0.92, associated with suppression of 3d and 4f magnetism, respectively. We also observe a turning point of AFM-FM ordering of Ce3+ moment at xc3 ≃ 0.37. The SC is absent in the phase diagram, which is attributed to the destruction to Cooper pair by Ce-FM fluctuations in the vicinity of xc1. We continue to investigate CeFeAs1−xPxO0.95F0.05. With the separation of xc1 and xc3, this chemical pressure results in a broad SC region 0≤ x ≤ 0.53, while the original HF behavior is driven away by 5% F− doping. Different roles of P and F dopings are addressed, and the interplay between SC and Ce-4f magnetism is also discussed. [ABSTRACT FROM AUTHOR]

We present low-temperature magnetization, magnetoresistance and specific heat measurements on the Kondo lattice compound CePt3P under applied magnetic fields up to 9.0 T. At zero field, CePt3P exhibits a moderately enhanced Sommerfeld coefficient of electronic specific heat γ Ce = 86 mJ/mol·K2 as well as two successive magnetic transitions of Ce 4f moments: an antiferromagnetic ordering at T N1 = 3.0K and a spin reorientation at T N2 = 1.9 K. The value of T N1 shifts to lower temperature as magnetic field increases, and it is ultimately suppressed around B c ∼ 3.0T at 1.5 K. No evidence of non-Fermi liquid behavior is observed around B c down to the lowest temperature measured. Moreover, γ decreases monotonously with increasing the magnetic field. On the other hand, the electrical resistivity shows an anomalous temperature dependence ρ ∝ T n with the exponent n decreasing monotonously from ∼2.6 around B c down to ∼1.7 for B = 9.0 T. The T–B phase diagram constructed from the present experimental results of CePt3P does not match the quantum criticality scenario of heavy fermion systems. [ABSTRACT FROM AUTHOR]

We investigate the anisotropic magnetic transports in topological semimetal TaSb2. The compound shows the large magnetoresistance (MR) without saturation and the metal-insulator-like transition no matter whether the magnetic field is parallel to c-axis or a-axis, except that the MR for B||c is almost twice as large as that of B||a at low temperatures. The adopted Kohler’s rule can be obeyed by the MR at distinct temperatures for B||c, but it is slightly violated as B||a. The angle-dependent MR measurements exhibit the two-fold rotational symmetry below 70 K, consistent with the monoclinic crystal structure of TaSb2. The dumbbell-like picture of angle-dependent MR in TaSb2 suggests a strongly anisotropic Fermi surface at low temperatures. However, it finally loses the two-fold symmetry over 70 K, implying a possible topological phase transition at around the temperature where Tm is related to a metal-insulator-like transition under magnetic fields. [ABSTRACT FROM AUTHOR]

Large single crystals of optimally doped Eu(Fe0.91Rh0.09)2As2 were grown by the self-flux method. Resistivity and magnetization measurements show that the compound undergoes a superconducting transition at 19.6 K, followed by a ferromagnetic ordering of the Eu2+ moments at 16.8 K. The upper critical fields at zero temperature are estimated to be 12.5 T and 15.1 T for fields along the ab plane and the c-axis, respectively. Moreover, anisotropy reversal of the upper critical field is observed near the magnetic ordering temperature, which may be related to the anisotropic magnetization of Eu ions and the demagnetization effect. Both ferromagnetic and superconducting features are displayed by the magnetic susceptibility and peculiar isothermal magnetization loop. Our combined results unambiguously demonstrate the coexistence of ferromagnetism and superconductivity in the title compound. [ABSTRACT FROM AUTHOR]