Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 24: Quantum-Critical Phenomena
TT 24.5: Vortrag
Mittwoch, 7. September 2022, 16:00–16:15, H23
Muon spin rotation and relaxation study on Nb1−yFe2+y — •Jannis Willwater1, Daniela Eppers1,2, Thomas Kimmel1, Elaheh Sadrollahi1,3, Jochen Litterst1, Malte Grosche4, Christopher Baines5, and Stefan Süllow1 — 1IPKM, TU Braunschweig, Germany — 2PTB, Braunschweig, Germany — 3IFMP, TU Dresden, Germany — 4Cavendish Laboratory, University of Cambridge, United Kingdom — 5PSI, Villigen, Switzerland
The study of metallic materials with a ferromagnetic quantum critical transition revealed a plethora of novel and exotic behavior. In Nb1−yFe2+y, a well-known example, the magnetic ground state reacts extremely sensitively to the chemical composition. Previous experiments show that by varying y, two ferromagnetic ultralow-moment and a SDW phase can be reached in the phase diagram. In particular, the magnetism disappears in a narrow range which is associated with the occurrence of a quantum critical point.
Here, we present a comprehensive study of the magnetic behaviour of Nb1−yFe2+y by means of muon spin rotation and relaxation. After establishing the muon stopping site, we studied and validated the magnetic phase diagram on different single and polycrystals. The focus of our study was the first investigation of a quantum critical sample, which shows no signs of long-range order, using a microscopic measurement technique. We demonstrate that magnetism at the lowest temperatures is dominated by magnetic fluctuations and that Nb1−yFe2+y emerges to be uniquely suited to study quantum criticality close to weak itinerant ferromagnetic order.