Quantum oscillations in the heavy-fermion compound YbPtBi

Abstract

We present quantum oscillations observed in the heavy fermion compound YbPtBi in magnetic fields far beyond its field-tuned, quantum critical point. Quantum oscillations are observed in magnetic fields as low as 60 kOe at 60 mK and up to temperatures as high as 3 K, which confirms the very high quality of the samples as well as the small effective mass of conduction carriers far from the quantum critical point. Although the electronic specific heat coefficient of YbPtBi reaches ∼ 7.4 J/mol K 2 in zero field, which is one of the highest effective mass value among heavy fermion systems, it is suppressed quickly by applied magnetic field. The quantum oscillations were used to extract the quasiparticle effective masses of the order of the bare electron mass, which is consistent with the behavior observed in specific heat measurements. Such a small effective masses at high fields can be understood by considering the suppression of Kondo screening.

Two-channel conduction in YbPtBi

“…These Drude terms have very different (by more than an order of magnitude) scattering rates, 1/τ . Analysis of Shubnikov-de Haas oscillations in YbPtBi yields the effective carrier masses m * close to the free-electron mass m e for any band, ranging from ∼ 0.5 to 1.5m e [7]. Thus, the large difference between the electron and hole mobilities in YbPtBi should be mostly related to the difference in the scattering rates (µ = eτ /m * ) and one can ascribe the Drude term with the smaller scattering rate (the narrow Drude) to the highly mobile electrons and the term with larger scattering rate (the broad Drude) to the holes with low mobility.…”

“…For 25 years YbPtBi was renowned as a heavy-fermion compound that exhibits one of the highest effective electron masses among the strongly correlated electron systems [1,2]. Its Kondo temperature is around 1 K; in addition an antiferromagnetic transition is observed at 0.4 K. So far, most of the experimental studies on YbPtBi explore its heavy-fermion state and a possible quantum critical point; hence they focus on temperatures below 2 K [1][2][3][4][5][6][7].…”

Magnetic-field effects on the fragile antiferromagnetism in YbBiPt

“…11,17 The presence of quantum oscillations in resistance data for µ 0 H 6 T at low temperature also evidences high-quality crystals. 20 The magnetic diffraction peaks are elastic within an energy-resolution window of ∆E = 0.09 meV, which means that within such energy resolution they correspond to static AFM order. 17 In this report, we present results from neutron diffraction experiments performed at T ≤ 0.75 K for applied magnetic fields strong enough to traverse the previously identified AFM and FL boundaries 7 .…”

Preserved entropy and fragile magnetism

“…By roughly 1 T there is a clear, low temperature Fermi liquid (FL) state with diverging values of the coefficient of T 2 resistivity and linear specific heat as H is decreased from higher values [23]. At much higher fields the heavy Fermi-liquid state is suppressed; by 7 T clear quantum oscillations are detected with electron masses all of order roughly unity [24]. Until recently, the missing, key data set, was detailed, microscopic, information about the magnetic ordering.…”

“…YbBiPt on the other hand, appears to be a classic QCP system. Although YbBiPt was discovered to be a HF system over 20 years ago [4,5], its proximity to quantum criticality as well as the microscopic details of its presumed magnetic order were only determined over the past few years [23,24,25,26]. As shown in Fig.…”