title: Crossover from a heavy fermion to intermediate valence state in noncentrosymmetric Yb2Ni12(P,As)7.
abstract: We report measurements of the physical properties and electronic structure of the hexagonal compounds Yb2Ni12Pn7 (Pn = P, As) by measuring the electrical resistivity, magnetization, specific heat and partial fluorescence yield x-ray absorption spectroscopy (PFY-XAS). These demonstrate a crossover upon reducing the unit cell volume, from an intermediate valence state in Yb2Ni12As7 to a heavy-fermion paramagnetic state in Yb2Ni12P7, where the Yb is nearly trivalent. Application of pressure to Yb2Ni12P7 suppresses TFL, the temperature below which Fermi liquid behavior is recovered, suggesting the presence of a quantum critical point (QCP) under pressure. However, while there is little change in the Yb valence of Yb2Ni12P7 up to 30 GPa, there is a strong increase for Yb2Ni12As7 under pressure, before a near constant value is reached. These results indicate that any magnetic QCP in this system is well separated from strong valence fluctuations. The pressure dependence of the valence and lattice parameters of Yb2Ni12As7 are compared and at 1 GPa, there is an anomaly in the unit cell volume as well as a change in the slope of the Yb valence, indicating a correlation between structural and electronic changes.
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: W B
authors.initials: WB
authors.lastname: Jiang
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: C Y
authors.initials: CY
authors.lastname: Guo
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Hu
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: J M
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: M
authors.initials: M
authors.lastname: Smidman
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Y F
authors.initials: YF
authors.lastname: Wang
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: T
authors.initials: T
authors.lastname: Shang
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Z W
authors.initials: ZW
authors.lastname: Cheng
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.
authors.forename: F
authors.initials: F
authors.lastname: Gao
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: H
authors.initials: H
authors.lastname: Ishii
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: K D
authors.initials: KD
authors.lastname: Tsuei
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: Y F
authors.initials: YF
authors.lastname: Liao
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: X
authors.initials: X
authors.lastname: Lu
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany.
authors.forename: L H
authors.initials: LH
authors.lastname: Tjeng
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: J M
authors.initials: JM
authors.lastname: Chen
authors.affiliation: Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou, 310058, China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: H Q
authors.initials: HQ
authors.lastname: Yuan