Abstract
New phases of matter emerge at the edge of magnetic instabilities, which can occur in materials with moments that are localized, itinerant or intermediate between these extremes. In local moment systems, such as heavy fermions, the magnetism can be tuned towards a zero-temperature transition at a quantum critical point (QCP) via pressure, chemical doping, and, rarely, magnetic field. By contrast, in itinerant moment systems, QCPs are more rare, and they are induced by pressure or doping; there are no known examples of field induced transitions. This means that no universal behaviour has been established across the whole itinerant-to-local moment range—a substantial gap in our knowledge of quantum criticality. Here we report an itinerant antiferromagnet, Ti3Cu4, that can be tuned to a QCP by a small magnetic field. We see signatures of quantum criticality and the associated non-Fermi liquid behaviour in thermodynamic and transport measurements, while band structure calculations point to an orbital-selective, spin density wave ground state, a consequence of the square net structural motif in Ti3Cu4. Ti3Cu4 thus provides a platform for the comparison and generalisation of quantum critical behaviour across the whole spectrum of magnetism.
| Original language | English |
|---|---|
| Article number | 136 |
| Journal | Communications Physics |
| Volume | 5 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2022 |
Funding
We are grateful to Bassam Hitti and Gerald Morris for their assistance with the muon spin relaxation measurements at TRIUMF. We are also grateful to Anand B. Puthirath for help with some characterization, as well as Warren Pickett and Jeffrey Lynn for useful conversations. We thank Ian Fisher and Pierre Massat for fruitful discussions on MCE measurements. JMM was supported by the National Science Foundation Graduate Research Fellowship under Grant DGE 1842494. CLH, SL and EM acknowledge support from NSF DMR 1903741. CLH is also supported by the Ministry of Science and Technology (MOST) in Taiwan under grant no. MOST 109-2112-M-006-026-MY3 and 110-2124-M-006-009. AMH, JB, YC, and GML were supported by the Natural Sciences and Engineering Research Council of Canada. VL and AHN were supported by the Robert A. Welch Foundation grant C-1818. AHN was also supported by the National Science Foundation grant no. DMR-1917511 and would like to thank for the hospitality of the Kavli Institute for Theoretical Physics, supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement No. DMR-1644779, the State of Florida and the United States Department of Energy. Use was made of the Integrated Molecular Structure Education and Research Center X-ray Facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental Resource (NSF Grant ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology. At Argonne, this work was supported by the US Department of Energy, Office of science, Basic Energy Sciences, Materials Sciences and Engineering Division (structural analysis). A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. We are grateful to Bassam Hitti and Gerald Morris for their assistance with the muon spin relaxation measurements at TRIUMF. We are also grateful to Anand B. Puthirath for help with some characterization, as well as Warren Pickett and Jeffrey Lynn for useful conversations. We thank Ian Fisher and Pierre Massat for fruitful discussions on MCE measurements. JMM was supported by the National Science Foundation Graduate Research Fellowship under Grant DGE 1842494. CLH, SL and EM acknowledge support from NSF DMR 1903741. CLH is also supported by the Ministry of Science and Technology (MOST) in Taiwan under grant no. MOST 109-2112-M-006-026-MY3 and 110-2124-M-006-009. AMH, JB, YC, and GML were supported by the Natural Sciences and Engineering Research Council of Canada. VL and AHN were supported by the Robert A. Welch Foundation grant C-1818. AHN was also supported by the National Science Foundation grant no. DMR-1917511 and would like to thank for the hospitality of the Kavli Institute for Theoretical Physics, supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement No. DMR-1644779, the State of Florida and the United States Department of Energy. Use was made of the Integrated Molecular Structure Education and Research Center X-ray Facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental Resource (NSF Grant ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology. At Argonne, this work was supported by the US Department of Energy, Office of science, Basic Energy Sciences, Materials Sciences and Engineering Division (structural analysis). A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.