Heavy-fermion superconductivity in CeCoIn₅at 2.3 K

Abstract

We report the observation of heavy-fermion superconductivity in CeCoIn 5 at T c = 2.3 K. When compared to the pressure-induced T c of its cubic relative CeIn 3 (T c ∼ 200 mK), the T c of CeCoIn 5 is remarkably high. We suggest that this difference may arise from magnetically mediated superconductivity in the layered crystal structure of CeCoIn 5. Superconductivity is distinct in the correlation often evident between structure and properties: certain crystal structures or substructures favour superconductivity [1]. In particular, what underlies this relationship in the high-T c cuprates and heavy-fermion materials, which border so closely on magnetically ordered phases, is of essential interest both fundamentally and in the search for new superconducting materials [2, 3]. For example, fully half of the known heavyfermion superconductors crystallize in the tetragonal ThCr 2 Si 2 structure, which is also the structure type of the La 2 CuO 4 family of high-T c superconductors [4]. For the cuprates, there is no consensus on the origin of the superconductivity, but their quasi-2D structure and proximity to magnetic order have been shown to be particularly favourable for an unconventional form of superconductivity in which a pairwise-attractive interaction among quasiparticles is mediated by magnetic correlations [5]. Here, we report the discovery of a possible heavy-fermion analogue of the cuprates, a new layered superconductor CeCoIn 5 , with the highest known ambient-pressure superconducting transition temperature T c in the class of heavy-fermion materials. Heavy-fermion superconductors are materials in which superconductivity emerges out of a normal state with strong electronic correlations. The presence of an appropriate magnetic ion-in this case Ce-enhances the effective mass m * of conduction electrons by several orders of magnitude [6]. In the more than twenty years since the first heavy-fermion superconductor was discovered (CeCu 2 Si 2) [7], only one other Ce-based material has been found that unambiguously shows superconductivity at ambient pressure: CeIrIn 5 [8]. Both of these materials exhibit rather complex phenomena and/or metallurgy, making their study challenging. The ground state of CeCu 2 Si 2 can be either antiferromagnetic or superconducting depending on very small changes in unit-cell volume or composition [9]; CeIrIn 5 shows zero resistivity near 1 K but does not produce a thermodynamic signature of superconductivity until

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

“…We also include for comparison zero-field C/T data from samples grown by other group. [13] The field-cooling and zero-field-cooling branches of low-field magnetization measurements split at roughly the same transition temperature, see Fig. 2 (b).…”

A Macrocyclic Chelator That Selectively Binds Ln4+ over Ln3+ by a Factor of 1029

“…47 For example, Ce L3-and M5,4-edge XANES spectroscopic investigations of CeRu3, CeRh3, and CePt3 have provided evidence for 4f-electron delocalization, 20,23,[48][49] and L3-edge investigations of intermetallics such as CeCoIn5 have led to new understanding of their remarkable magnetic and superconducting properties. [50][51][52][53][54] The pace of synthetic, experimental, and theoretical progress has been impeded recently due to sample purity concerns, uncertainty regarding the interpretation of complex spectral phenomena, and the validity of theoretical approximations required to model periodic systems.…”

Nonmagnetic impurity resonance states as a test of superconducting pairing symmetry in CeCoIn5

“…Recently, the interplay of antiferromagnetic (AF) order and unconventional superconductivity in Ce-based heavy fermion superconductors CeMIn 5 (M = Co, Rh, Ir) have been intensively studied [1][2][3][4][5][6][7][8][9][10][11][12][13] . For instance, CeCoIn 5 is a superconductor with the highest transition temperature T c ≈ 2.3K whereas CeRhIn 5 orders antiferromagnetically below T N ≈ 3.7K 9 .…”