Browsing by Author "Rai, Binod K."

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    Anomalous Metamagnetism in the Low Carrier Density Kondo Lattice YbRh3Si7
    (American Physical Society, 2018) Rai, Binod K.; Chikara, S.; Ding, Xiaxin; Oswald, Iain W.H.; Schönemann, R.; Loganathan, V.; Hallas, A.M.; Cao, H.B.; Stavinoha, Macy; Chen, T.; Man, Haoran; Carr, Scott; Singleton, John; Zapf, Vivien; Benavides, Katherine A.; Chan, Julia Y.; Zhang, Q.R.; Rhodes, D.; Chiu, Y.C.; Balicas, Luis; Aczel, A.A.; Huang, Q.; Lynn, Jeffrey W.; Gaudet, J.; Sokolov, D.A.; Walker, H.C.; Adroja, D.T.; Dai, Pengcheng; Nevidomskyy, Andriy H.; Huang, C.-L.; Morosan, E.
    We report complex metamagnetic transitions in single crystals of the new low carrier Kondo antiferromagnet YbRh3Si7. Electrical transport, magnetization, and specific heat measurements reveal antiferromagnetic order at TN=7.5 K. Neutron diffraction measurements show that the magnetic ground state of YbRh3Si7 is a collinear antiferromagnet, where the moments are aligned in the ab plane. With such an ordered state, no metamagnetic transitions are expected when a magnetic field is applied along the c axis. It is therefore surprising that high-field magnetization, torque, and resistivity measurements with H∥c reveal two metamagnetic transitions at μ0H1=6.7 T and μ0H2=21 T. When the field is tilted away from the c axis, towards the ab plane, both metamagnetic transitions are shifted to higher fields. The first metamagnetic transition leads to an abrupt increase in the electrical resistivity, while the second transition is accompanied by a dramatic reduction in the electrical resistivity. Thus, the magnetic and electronic degrees of freedom in YbRh3Si7 are strongly coupled. We discuss the origin of the anomalous metamagnetism and conclude that it is related to competition between crystal electric-field anisotropy and anisotropic exchange interactions.
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    CeIr3Ge7: A local moment antiferromagnetic metal with extremely low ordering temperature
    (American Physical Society, 2018) Rai, Binod K.; Banda, Jacintha; Stavinoha, Macy; Borth, R.; Jang, D.-J.; Benavides, Katherine A.; Sokolov, D. A.; Chan, Julia Y.; Nicklas, M.; Brando, Manuel; Huang, C.-L.; Morosan, E.
    CeIr3Ge7 is an antiferromagnetic metal with a remarkably low ordering temperature TN=0.63K, while most Ce-based magnets order between 2 and 15 K. Thermodynamic and transport properties as a function of magnetic field or pressure do not show signatures of Kondo correlations, interaction competition, or frustration, as had been observed in a few antiferromagnets with comparably low or lower TN. The averaged Weiss temperature measured below 10 K is comparable to TN, suggesting that the Ruderman-Kittel-Kasuya-Yosida exchange coupling is very weak in this material. The unusually low TN in CeIr3Ge7 can therefore be attributed to the large Ce-Ce bond length of about 5.7 Å, which is about 1.5 Å larger than in the most Ce-based intermetallic systems.
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    Intermediate valence in single crystals of (Lu1−x Y b x )3Rh4Ge13 (0 ≤ x ≤ 1)
    (AIP Publishing LLC, 2015) Rai, Binod K.; Morosan, E.
    Single crystals of (Lu1−x Y b x )3Rh4 Ge 13 were characterized by magnetization, specific heat, and electrical resistivity measurements. Doping Yb into the non-magnetic Lu3Rh4 Ge 13 compound tunes this cubic system’s properties from a superconductor with disordered metal normal state (x < 0.05) to a Kondo for 0.05 ≤ x ≤0.2 and intermediate valence at the highest Yb concentrations. The evidence for intermediate Yb valence comes from a broad maximum in the magnetic susceptibility and X-ray photoelectron spectroscopy. Furthermore, the resistivity displays a local maximum at finite temperatures at intermediate compositions x, followed by apparent metallic behavior closest to the Yb end compound in the series.
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    Intermediate valence to heavy fermion through a quantum phase transition in Yb3(Rh1−xTx)4Ge13 (T=Co,Ir) single crystals
    (American Physical Society, 2016) Rai, Binod K.; Oswald, Iain W.H.; Chan, Julia Y.; Morosan, E.
    Single crystals of Yb3(Rh1−xTx)4Ge13 (T=Co,Ir) have been grown using the self-flux method. Powder x-ray diffraction data on these compounds are consistent with the cubic structure with space group Pm3¯n. Intermediate-valence behavior is observed in Yb3(Rh1−xTx)4Ge13 upon T = Co doping, while T = Ir doping drives the system into a heavy-fermion state. Antiferromagnetic order is observed in the Ir-doped samples Yb3(Rh1−xTx)4Ge13 for 0.5
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    Low-carrier density and fragile magnetism in a Kondo lattice system
    (American Physical Society, 2019) Rai, Binod K.; Oswald, Iain W.H.; Ban, Wenjing; Huang, C.-L.; Loganathan, V.; Hallas, A.M.; Wilson, M.N.; Luke, G.M.; Harriger, L.; Huang, Q.; Li, Y.; Dzsaber, Sami; Chan, Julia Y.; Wang, N.L.; Paschen, Silke; Lynn, J.W.; Nevidomskyy, Andriy H.; Dai, Pengcheng; Si, Q.; Morosan, E.; Rice Center for Quantum Materials
    Kondo-based semimetals and semiconductors are of extensive current interest as a viable platform for strongly correlated states in the dilute carrier limit. It is thus important to explore the routes to understand such systems. One established pathway is through the Kondo effect in metallic nonmagnetic analogs, in the so called half-filling case of one conduction electron and oneﾠ4fﾠelectron per site. Here, we demonstrate that Kondo-based semimetals develop out of conduction electrons with a low-carrier density in the presence of an even number of rare-earth sites. We do so by studying the Kondo materialﾠYb3Ir4Ge13ﾠalong with its closed-4f-shell counterpart,ﾠLu3Ir4Ge13. Through magnetotransport, optical conductivity, and thermodynamic measurements, we establish that the correlated semimetallic state ofﾠYb3Ir4Ge13ﾠbelow its Kondo temperature originates from the Kondo effect of a low-carrier conduction-electron background. In addition, it displays fragile magnetism at very low temperatures, which in turn, can be tuned to a Griffiths-phase-like regime through Lu-for-Yb substitution. These findings are connected with recent theoretical studies in simplified models. Our results can pave the way to exploring strong correlation physics in a semimetallic environment.