Conference Presentation (Invited)

FZJ-2026-02065

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Polarized Neutron Scattering Studies on SDW Order in Sr1.5Ca0.5RuO4 andSr2Ru0.95Co0.05O4

Wirth, F. ; Sidis, Y. ; Steffens, P. ; Jenni, K. ; Agung Nugroho, A. ; Schmalzl, K.FZJ* ; Enderle, M. ; Braden, M.

2026

Abstract: Superconductivity in Sr2RuO4 emerges close to magnetic instabilitiesfrom Fermi-surface nesting at incommensurate Qαβ ≈(0.3,0.3,L) andQγ ≈(0.15,0.15,L)[1]. In Sr1.5Ca0.5RuO4 the anisotropic fluctuations at Qαβ condense into a c-axis polarized spin-density-wave[2]. Polarized inelastic neutronscattering reveals an unusual hierarchy of excitations with enhanced longitudinalmodes. In contrast, transverse modes are suppressed, although theirenergy dependence remains similar to that of the parent compound. Above theSDWtransition, longitudinal and transverse contributions show a split response,incompatible with tetragonal symmetry and suggestive of electronic nematicity.Ti4+ andMn3+ substitution stabilise the same static order at Qαβ[3]. By contrast,5% Co doping does not yield the expected ferromagnetic cluster glass but a newmagnetic order at Q≈(0.2,0.2,0) with intensity following the Ru4+ form factorthat cannot be attributed to the known nesting vectors in this system. [1] Jenni,K. et al., Phys. Rev. B 103, 104511 (2021), [2] Kunkemoller, S. et al., Phys. Rev.B 89, 045119 (2014), [3] Braden, M. et al., Phys. Rev. Lett. 88, 197002 (2002)

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Contributing Institute(s):

1. Streumethoden (JCNS-2)
2. JARA-FIT (JARA-FIT)
3. JCNS-ILL (JCNS-ILL)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ) (POF4-6G4) (POF4-6G4)

Appears in the scientific report 2026

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