|Title||NMR study of the new magnetic superconductor CaK(Fe0.951Ni0.049)(4)As-4: Microscopic coexistence of the hedgehog spin-vortex crystal and superconductivity|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Ding, QP, Meier, WR, Bohmer, AE, Bud'ko, SL, Canfield, PC, Furukawa, Y|
|Journal||Physical Review B|
|Type of Article||Article|
The coexistence of a new-type antiferromagnetic (AFM) state, the so-called hedgehog spin-vortex crystal (SVC), and superconductivity (SC) is evidenced by an As-75 nuclear magnetic resonance study on single-crystalline CaK(Fe0.951Ni0.049)(4)As-4. The hedgehog SVC order is clearly demonstrated by the direct observation of internal magnetic induction along the c axis at the As1 site (close to K) and a zero net internal magnetic induction at the As2 site (close to Ca) below an AFM ordering temperature T-N similar to 52 K. The nuclear spin-lattice relaxation rate 1/T-1 shows a distinct decrease below T-c similar to 10 K, providing also unambiguous evidence for the microscopic coexistence. Furthermore, based on the analysis of the 1/T-1 data, the hedgehog SVC-type spin correlations are found to be enhanced below T similar to 150 K in the paramagnetic state. These results indicate the hedgehog SVC-type spin correlations play an important role for the appearance of SC in the new magnetic superconductor.
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