How ground states of quantum matter transform between one another reveals deep insights into the mechanisms stabilizing them. Correspondingly, quantum phase transitions are explored in numerous materials classes, with heavy fermion compounds being among the most prominent ones. Recent studies in an anisotropic heavy fermion compound have shown that different types of transitions are induced by variations of chemical or external pressure 1-3 , raising the question of the extent to which heavy fermion quantum criticality is universal.To make progress, it is essential to broaden both the materials basis and the microscopic parameter variety. Here, we identify a cubic heavy fermion material as exhibiting a field-induced quantum phase transition, and show how the material can be used to explore one extreme of the dimensionality axis. The transition between two different ordered phases is accompanied by an abrupt change of Fermi surface, reminiscent of what happens across the field-induced antiferromagnetic to paramagnetic transition in the anisotropic YbRh 2 Si 2 . This finding leads to a materials-based global phase diagram -a precondition for a unified theoretical description.1 Quantum phase transitions arise in matter at zero temperature due to competing interactions. When they are continuous, the associated quantum critical points (QCPs) give rise to collective excitations which influence the physical properties over a wide range of parameters. As such, they are being explored in a variety of electronic materials, ranging from high T c cuprates to insulating magnets and quantum Hall systems 4,5 .Heavy fermion compounds are prototype materials to study quantum phase transitions. Their low energy scales allow to induce such transitions deliberately, by the variation of external parameters such as pressure or magnetic field. Microscopically, electrons in partiallyfilled f shells behave as localized magnetic moments. They interact with conduction electrons through a Kondo exchange interaction, which favors a non-magnetic ground state that entangles the local moments and the spins of the conduction electrons. They also interact among themselves through an RKKY exchange interaction, which typically induces antiferromagnetic order. It has been known that tuning external parameters changes the ratio of the Kondo coupling to the RKKY interaction. Recently, the importance of a second microscopic quantity has been suggested. This is the degree of quantum fluctuations of the local moments, parameterized by G: magnetic order weakens with increasing G, as it would with enhancing the Kondo coupling J K . These two quantities define a two-dimensional parameter space, which allows the consideration of a global phase diagram 10 . This global phase diagram is most clearly specified via the energy scale T * associated with the breakdown of the Kondo entanglement between the local moments and conduction electrons. So far T * has only been identified in tetragonal YbRh 2 Si 2 (refs. 8,11,12 ). It is believed that this energy scale no...

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CeAuSb 2 has previously been classified as an antiferromagnet with moderately enhanced electron masses. As the magnetic order is suppressed by a magnetic field, non-Fermi liquid behaviour has been shown to emerge, suggesting the presence of a quantum critical point (QCP). Within the ordered phase a metamagnetic transition was detected. Here we investigate the material by isothermal magnetization M(H), transverse magnetoresistivity r t (H) and Hall resistivity r H (H) measurements. We show that the metamagnetic transition splits into two first order transitions below 2 K. Pronounced anomalies in r t (H) and r H (H) are not only observed at the QCP and the metamagnetic transitions but also at a new characteristic field above the QCP.

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We study the evolution of the magnetic ground state close to the putative quantum critical point in CeCoGe 2.2 Si 0.8 by using electrical resistivity and specific heat measurements under the same high hydrostatic pressure conditions. The electrical resistivity shows that the antiferromagnetic ordering temperature, T N , is suppressed above P C ¼ 5.9 kbar, with the emergence of non-Fermi liquid behavior. On the other hand, the specific heat shows two different magnetic transitions at 0 kbar, one at T N and another one at T l % 0.3 K. Both transition temperatures are reduced by pressure but remain finite up to at least 7.2 kbar. The height of the specific heat anomaly at T N , DC N , is strongly reduced above P C . These features suggest that the quantum criticality in CeCoGe 2.2 Si 0.8 is governed by disorder.1 Introduction Investigations of the role that disorder plays in strongly correlated electron materials close to a quantum critical point (QCP) have awaken a lot of interest during the last decade [1][2][3][4]. An open issue [5] is to understand how for systems with translational invariant symmetry disorder changes the universal quantum criticality and the low-lying energy scales that emerge in the vicinity of the phase transition at T ¼ 0 K. The pseudo-ternary heavy fermion (HF) system CeCoGe 3-x Si x [6] with tetragonal BaNiSn 3 -type structure and antiferromagnetic (AF) order between 0.5 < x 1 has been claimed to be dominated by the disordered Griffiths phase at its doping-induced QCP [7]. A recent investigation using electrical resistivity, r(T), under hydrostatic high pressure, P, on the AF HF compound x ¼ 0.9 [8] has revealed that the P-tuned QCP (P C ¼ 6.2 kbar) is dominated by different effects on both sides of the QCP: on the magnetic side spin fluctuations govern the criticality, while on the non-magnetic side the criticality is dominated by disorder that quenches the spin fluctuations. More recently, we have performed DC-magnetic susceptibility, x(T), measurements under high P on a sample with x ¼ 0.8 [9], a composition close to that reported in previous r(T) measurements. Our results suggested that a spin glass-like