Low-Temperature Properties of CePt_3P Tuned by Magnetic Field

We present low-temperature magnetization, magnetoresistance and specific heat measurements on the Kondo lattice compound CePt_3P under applied magnetic fields up to 9.0 T. At zero field, CePt_3P exhibits a moderately enhanced Sommerfeld coefficient of electronic specific heat γCe=86 mJ/mol·K^2 as well as two successive magnetic transitions of Ce 4f moments: an antiferromagnetic ordering at T_(N_1) = 3.0 K and a spin reorientation at T_(N_2)=1.9 K. The value of T_(N_1) shifts to lower temperature as magnetic field increases, and it is ultimately suppressed around B_c ～3.0 T 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 CePt_3P does not match the quantum criticality scenario of heavy fermion systems.

Combined Study of Structural, Magnetic and Transport Properties of Eu_(0.5)Ln_(0.5)BiS_(2)F Superconductor

Superconductivity below 0.3 K and a charge-density-wave-like(CDW-like) anomaly at 280 K were observed in EuBiS_(2)F recently.Here we report a systematic study of structural and transport properties in Eu_(0.5)Ln_(0.5)BiS_(2)F(Ln=La,Ce,Pr,Nd,Sm) by electrical resistivity,magnetization,and specific heat measurements.The lattice constants have a significant change upon rare earth substitution for Eu,suggesting an effective doping.As Ln is changed from Sm to La,the superconducting transition temperature T_(c) increases from 1.55 K to 2.8 K.In contrast to the metallic parent compound,the temperature dependence of electrical resistivity displays semiconductinglike behavior for all the Eu_(0.5)Ln_(0.5)BiS_(2)F samples.Meanwhile,the CDW-like anomaly observed in EuBiS2F is completely suppressed.Unlike the mixed valence state in the undoped compound,Eu ions in these rareearth-doped samples are mainly divalent.A specific anomaly at 1.3 K resembling that in EuBiS_(2)F suggests the coexistence of superconductivity and spin glass state for Eu_(0.5)Ln_(0.5)BiS_(2)F.Coexistence of ferromagnetic order and superconductivity is found below 2.2 K in Eu_(0.5)Ln_(0.5)BiS_(2)F samples.Our results supplies a rich diagram showing that many interesting properties can be induced in BiS_(2)-based compounds.