G. Koutroulakis

Field Evolution of Coexisting Superconducting and Magnetic Orders in CeCoIn5

We present nuclear magnetic resonance (NMR) measurements on the three distinct In sites of CeCoIn5 with a magnetic field applied in the [100] direction. We identify the microscopic nature of the long range magnetic order (LRO) stabilized at low temperatures in fields above 10.2 T while still in the superconducting (SC) state. We infer that the ordered moment is oriented along the c axis and map its field evolution. The study of the field dependence of the NMR shift for the different In sites indicates that the LRO likely coexists with a modulated SC phase, possibly that predicted by Fulde, Ferrell, Larkin, and Ovchinnikov. Furthermore, we discern a field region dominated by strong spin fluctuations where static LRO is absent and propose a revised phase diagram.

Field dependence of the ground state in the exotic superconductor CeCoIn5: a nuclear magnetic resonance investigation.

We report 115In nuclear magnetic resonance (NMR) measurements in CeCoIn5 at low temperature (T approximately 70 mK) as a function of the magnetic field (H0) from 2 to 13.5 T applied perpendicular to the c axis. A NMR line shift reveals that below 10 T the spin susceptibility increases as sqrt[H0]. We associate this with an increase of the density of states due to the Zeeman and Doppler-shifted quasiparticles extended outside the vortex cores in a d-wave superconductor. Above 10 T a new superconducting state is stabilized, possibly the modulated phase predicted by Fulde, Ferrell, Larkin, and Ovchinnikov. This phase is clearly identified by a strong and linear increase of the NMR shift with the field, before a jump at the first order transition to the normal state.

Anisotropic transferred hyperfine interactions in Cs2CuCl4

We report 133Cs nuclear magnetic resonance (NMR) measurements of magnetic insulator Cs2CuCl4 in the paramagnetic phase (T≥4.2 K) as a function of the orientation of an applied magnetic field with respect to the principal crystalline axes. The magnetic shift tensor is determined. It is found that its principal axes do not coincide with the principal axes of the crystal. The Cu–Cs dipolar interaction tensor is calculated as well. From these, we deduce the full transferred hyperfine tensor for the two inequivalent Cs sites of the unit cell. We find that the tensors are anisotropic, containing non-zero off-diagonal terms, and that the transferred hyperfine coupling between Cu electronic spins and Cs nuclei dominates the NMR shift on both Cs sites.

Phase diagram of CeCoIn5CeCoIn5 in the vicinity of Hc2Hc2 as determined by NMR

We report In115 nuclear magnetic resonance (NMR) measurements in the heavy-fermion superconductor CeCoIn5CeCoIn5 as a function of temperature in different magnetic fields applied parallel to the (a^,b^) plane. The measurements probe a part of the phase diagram in the vicinity of the superconducting critical field Hc2Hc2 where a possible inhomogeneous superconducting state, Fulde–Ferrel–Larkin–Ovchinnikov (FFLO), is stabilized. We have identified clear NMR signatures of two phase transitions occurring in this part of the phase diagram. The first order phase transitions are characterized by the sizable discontinuity of the shift. We find that a continuous second-order phase transition from the superconducting to the FFLO state occurs at temperature below which the shift becomes temperature independent. We have compiled the first phase diagram of CeCoIn5CeCoIn5 in the vicinity of Hc2Hc2 from NMR data and found that it is in agreement with the one determined by thermodynamic measurements.

Phase Diagram of CeCoIn_5 in the Vicinity of H_{c2} as Determined by NMR

We report In115 nuclear magnetic resonance (NMR) measurements in the heavy-fermion superconductor CeCoIn5CeCoIn5 as a function of temperature in different magnetic fields applied parallel to the (a^,b^) plane. The measurements probe a part of the phase diagram in the vicinity of the superconducting critical field Hc2Hc2 where a possible inhomogeneous superconducting state, Fulde–Ferrel–Larkin–Ovchinnikov (FFLO), is stabilized. We have identified clear NMR signatures of two phase transitions occurring in this part of the phase diagram. The first order phase transitions are characterized by the sizable discontinuity of the shift. We find that a continuous second-order phase transition from the superconducting to the FFLO state occurs at temperature below which the shift becomes temperature independent. We have compiled the first phase diagram of CeCoIn5CeCoIn5 in the vicinity of Hc2Hc2 from NMR data and found that it is in agreement with the one determined by thermodynamic measurements.

Phase diagram of CeCoIn5 in the vicinity of Hc2 as determined by NMR

We report In115 nuclear magnetic resonance (NMR) measurements in the heavy-fermion superconductor CeCoIn5CeCoIn5 as a function of temperature in different magnetic fields applied parallel to the (a^,b^) plane. The measurements probe a part of the phase diagram in the vicinity of the superconducting critical field Hc2Hc2 where a possible inhomogeneous superconducting state, Fulde–Ferrel–Larkin–Ovchinnikov (FFLO), is stabilized. We have identified clear NMR signatures of two phase transitions occurring in this part of the phase diagram. The first order phase transitions are characterized by the sizable discontinuity of the shift. We find that a continuous second-order phase transition from the superconducting to the FFLO state occurs at temperature below which the shift becomes temperature independent. We have compiled the first phase diagram of CeCoIn5CeCoIn5 in the vicinity of Hc2Hc2 from NMR data and found that it is in agreement with the one determined by thermodynamic measurements.

Phase diagram of in the vicinity of as determined by NMR

We report In115 nuclear magnetic resonance (NMR) measurements in the heavy-fermion superconductor CeCoIn5CeCoIn5 as a function of temperature in different magnetic fields applied parallel to the (a^,b^) plane. The measurements probe a part of the phase diagram in the vicinity of the superconducting critical field Hc2Hc2 where a possible inhomogeneous superconducting state, Fulde–Ferrel–Larkin–Ovchinnikov (FFLO), is stabilized. We have identified clear NMR signatures of two phase transitions occurring in this part of the phase diagram. The first order phase transitions are characterized by the sizable discontinuity of the shift. We find that a continuous second-order phase transition from the superconducting to the FFLO state occurs at temperature below which the shift becomes temperature independent. We have compiled the first phase diagram of CeCoIn5CeCoIn5 in the vicinity of Hc2Hc2 from NMR data and found that it is in agreement with the one determined by thermodynamic measurements.