Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMagnetism and unconventional superconductivity in Ce$_n$M$_m$In$_{3n+2m}$ heavy-fermion crystals
120
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We review magnetic, superconducting and non-Fermi-liquid properties of the structurally layered heavy-fermion compounds Ce$_n$M$_m$In$_{3n+2m}$ (M=Co, Rh, Ir). These properties suggest d-wave superconductivity and proximity to an antiferromagetic quantum-critical point.
rate research
Read More
We grew single crystals of the recently discovered heavy fermion superconductor UTe2, and measured the resistivity, specific heat and magnetoresistance. Superconductivity (SC) was clearly detected at Tsc=1.65K as sharp drop of the resistivity in a high quality sample of RRR=35. The specific heat shows a large jump at Tsc indicating strong coupling. The large Sommerfeld coefficient, 117mJ K-2mol-1 extrapolated in the normal state and the temperature dependence of C/T below Tsc are the signature of unconventional SC. The discrepancy in the entropy balance at Tsc between SC and normal states points out that hidden features must occur. Surprisingly, a large residual value of the Sommerfeld coefficient seems quite robust (gamma_0/gamma ~ 0.5). The large upper critical field Hc2 along the three principal axes favors spin-triplet SC. For H // b-axis, our experiments do not reproduce the huge upturn of Hc2 reported previously. This discrepancy may reflect that Hc2 is very sensitive to the sample quality. A new perspective in UTe2 is the proximity of a Kondo semiconducting phase predicted by the LDA band structure calculations.
The interplay of magnetism and unconventional superconductivity (d singlet wave or p triplet wave) in strongly correlated electronic system (SCES) is discussed with recent examples found in heavy fermion compounds. A short presentation is given on the formation of the heavy quasiparticle with the two sources of a local and intersite enhancement for the effective mass. Two cases of the coexistence or repulsion of antiferromagnetism and superconductivity are given with CeIn3 and CeCoIn5. A spectacular example is the emergence of superconductivity in relatively strong itinerant ferromagnets UGe2 and URhGe. The impact of heavy fermion matter among other SCES as organic conductor or high Tc oxide is briefly pointed out.
We report the observation of heavy-fermion superconducitivity in CeCoIn5 at Tc =2.3 K. When compared to the pressure-induced Tc of its cubic relative CeIn3 (Tc ~200 mK), the Tc of CeCoIn5 is remarkably high. We suggest that this difference may arise from magnetically mediated superconductivity in the layered crystal structure of CeCoIn5 .
We report on the pressure-induced unconventional superconductivity in the heavy-fermion antiferromagnet CeIn3 by means of nuclear-quadrupole-resonance (NQR) studies conducted under a high pressure. The temperature and pressure dependences of the NQR spectra have revealed a first-order quantum-phase transition (QPT) from an AFM to PM at a critical pressure Pc=2.46 GPa. Despite the lack of an AFM quantum critical point in the P-T phase diagram, we highlight the fact that the unconventional SC occurs in both phases of the AFM and PM. The nuclear spin-lattice relaxation rate 1/T1 in the AFM phase have provided evidence for the uniformly coexisting AFM+SC phase. In the HF-PM phase where AFM fluctuations are not developed, 1/T1 decreases without the coherence peak just below Tc, followed by a power-law like T dependence that indicates an unconventional SC with a line-node gap. Remarkably, Tc has a peak around Pc in the HF-PM phase as well as in the AFM phase. In other words, an SC dome exists with a maximum value of Tc = 230 mK around Pc, indicating that the origin of the pressure-induced HF SC in CeIn3 is not relevant to AFM spin fluctuations but to the emergence of the first-order QPT in CeIn3. When the AFM critical temperature is suppressed at the termination point of the first-order QPT, Pc = 2.46 GPa, the diverging AFM spin-density fluctuations emerge at the critical point from the AFM to PM. The results with CeIn3 leading to a new type of quantum criticality deserve further theoretical investigations.
$rm CePt_3Si$ is a novel heavy fermion superconductor, crystallising in the $rm CePt_3B$ structure as a tetragonally distorted low symmetry variant of the $rm AuCu_3$ structure type. $rm CePt_3Si$ exhibits antiferromagnetic order at $T_N approx 2.2$ K and enters into a heavy fermion superconducting state at $T_c approx 0.75$ K. Large values of $H_{c2} approx -8.5$ T/K and $H_{c2}(0) approx 5$ T refer to heavy quasiparticles forming Cooper pairs. Hitherto, $rm CePt_3Si$ is the first heavy fermion superconductor without a center of symmetry.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
