### Abstract

A magnetic order can be completely suppressed at zero temperature (T), by doping carriers or applying pressure, at a quantum critical point, around which physical properties change drastically. However, the situation is unclear for an electronic nematic order that breaks rotation symmetry. Here, we report nuclear magnetic resonance studies on NaFe1-xCoxAs where magnetic and nematic transitions are well separated. The nuclear magnetic resonance spectrum is sensitive to inhomogeneous magnetic fields in the vortex state, which is related to London penetration depth λL that measures the electron mass m∗. We discovered two peaks in the doping dependence of λL2(T∼0), one at xM=0.027 where the spin-lattice relaxation rate shows quantum critical behavior, and another at xc=0.032 around which the nematic transition temperature extrapolates to zero and the electrical resistivity shows a T-linear variation. Our results indicate that a nematic quantum critical point lies beneath the superconducting dome at xc where m∗ is enhanced. The impact of the nematic fluctuations on superconductivity is discussed.

Original language | English |
---|---|

Article number | 167004 |

Journal | Physical Review Letters |

Volume | 121 |

Issue number | 16 |

DOIs | |

Publication status | Published - Oct 19 2018 |

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### ASJC Scopus subject areas

- Physics and Astronomy(all)

### Cite this

*Physical Review Letters*,

*121*(16), [167004]. https://doi.org/10.1103/PhysRevLett.121.167004

**Electron Mass Enhancement near a Nematic Quantum Critical Point in NaFe1-xCoxAs.** / Wang, C. G.; Li, Z.; Yang, J.; Xing, L. Y.; Dai, G. Y.; Wang, X. C.; Jin, C. Q.; Zhou, R.; Zheng, Guo-Qing.

Research output: Contribution to journal › Article

*Physical Review Letters*, vol. 121, no. 16, 167004. https://doi.org/10.1103/PhysRevLett.121.167004

}

TY - JOUR

T1 - Electron Mass Enhancement near a Nematic Quantum Critical Point in NaFe1-xCoxAs

AU - Wang, C. G.

AU - Li, Z.

AU - Yang, J.

AU - Xing, L. Y.

AU - Dai, G. Y.

AU - Wang, X. C.

AU - Jin, C. Q.

AU - Zhou, R.

AU - Zheng, Guo-Qing

PY - 2018/10/19

Y1 - 2018/10/19

N2 - A magnetic order can be completely suppressed at zero temperature (T), by doping carriers or applying pressure, at a quantum critical point, around which physical properties change drastically. However, the situation is unclear for an electronic nematic order that breaks rotation symmetry. Here, we report nuclear magnetic resonance studies on NaFe1-xCoxAs where magnetic and nematic transitions are well separated. The nuclear magnetic resonance spectrum is sensitive to inhomogeneous magnetic fields in the vortex state, which is related to London penetration depth λL that measures the electron mass m∗. We discovered two peaks in the doping dependence of λL2(T∼0), one at xM=0.027 where the spin-lattice relaxation rate shows quantum critical behavior, and another at xc=0.032 around which the nematic transition temperature extrapolates to zero and the electrical resistivity shows a T-linear variation. Our results indicate that a nematic quantum critical point lies beneath the superconducting dome at xc where m∗ is enhanced. The impact of the nematic fluctuations on superconductivity is discussed.

AB - A magnetic order can be completely suppressed at zero temperature (T), by doping carriers or applying pressure, at a quantum critical point, around which physical properties change drastically. However, the situation is unclear for an electronic nematic order that breaks rotation symmetry. Here, we report nuclear magnetic resonance studies on NaFe1-xCoxAs where magnetic and nematic transitions are well separated. The nuclear magnetic resonance spectrum is sensitive to inhomogeneous magnetic fields in the vortex state, which is related to London penetration depth λL that measures the electron mass m∗. We discovered two peaks in the doping dependence of λL2(T∼0), one at xM=0.027 where the spin-lattice relaxation rate shows quantum critical behavior, and another at xc=0.032 around which the nematic transition temperature extrapolates to zero and the electrical resistivity shows a T-linear variation. Our results indicate that a nematic quantum critical point lies beneath the superconducting dome at xc where m∗ is enhanced. The impact of the nematic fluctuations on superconductivity is discussed.

UR - http://www.scopus.com/inward/record.url?scp=85055214242&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85055214242&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.121.167004

DO - 10.1103/PhysRevLett.121.167004

M3 - Article

C2 - 30387623

AN - SCOPUS:85055214242

VL - 121

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 16

M1 - 167004

ER -