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9/13-17/04. Universal Workshop on Frustrated Magnetism. 2. Colleagues. Ruthenium pyrochloresK. H. Kim Rutgers N. HurRutgersD. AdrojaISISQ. HuangNISTS.- W. CheongRutgersT. G. PerringISISIridium pyrochloresSatoru NakatsujiKyoto Yo MachidaKyotoYoshiteru Maeno KyotoToshiro Sakakibara ISSPTakashi TayamaISSP.

Level Splitting in Frustrated non-Kramers doublet frameworks Spin Fluctuations in Metallic Pyrochlore Systems Collin Broholm and Joost van Duijn Department of Physics and Astronomy Johns Hopkins University

Collaborators Ruthenium pyrochlores K. H. Kim Rutgers N. Hur Rutgers D. Adroja ISIS Q. Huang NIST S.- W. Cheong Rutgers T. G. Perring ISIS Iridium pyrochlores Satoru Nakatsuji Kyoto Yo Machida Kyoto Yoshiteru Maeno Kyoto Toshiro Sakakibara ISSP Takashi Tayama ISSP International Workshop on Frustrated Magnetism

Outline Introduction Bulk properties of 4d n and 5d n pyrochlores Spin relationships on TM destinations Crystal field excitations on RE locales Level part in Pr x Bi 2-x Ru 2 O 7 Ground state doublet turn flow Model of inhomogeneous level part Discussion and Conclusions Possible importance for other non-Kramers doublet frameworks International Workshop on Frustrated Magnetism

An and B destinations on vertices of corner-sharing tetrahedra A 3+ site is trivalent RE with 8-crease O 2-coordination B 4+ site is tetravalent TM with 6-overlap O 2-coordination Can have both A 3+ and B 4+ attraction The pyrochlore structure A 2 B 2 O 7 International Workshop on Frustrated Magnetism

B=Ru site attraction of Y 2 Ru 2 O 7 Taira et al. (2000) Taira et al. (1999) Neutron Diffraction uncovers long range attractive request ZFC/FC hysteresis recommends some type of turmoil that produces smooth inclined AFM International Workshop on Frustrated Magnetism

T=1.5 K "Solid Coupling" Transition in Y 2 Ru 2 O 7 T=90 K International Workshop on Frustrated Magnetism

1.5 K 1.5 K 90 K 90 K PM and AFM Spin Fluctuations Phase Transition pushes huge otherworldly weight into "reverberation" The Q-reliance of diffusing mirrors the shape calculate for AFM bunch degrees of opportunity International Workshop on Frustrated Magnetism

2 Magnetic Ions 2 Phase Transitions R 2 Ru 2 O 7 Er 2 Ru 2 O 7 Pr 3+ M. Ito et al. (2001) Yb 3+ N. Taira et al. (2003) International Workshop on Frustrated Magnetism

Bi-doping increment transfer speed bringing about Mott Hubbard MIT Magnet request is discovered just in the protecting state Electronic DOS at E F is improved near the MIT Metal Insulator Transition Yoshii and Sato (1999) International Workshop on Frustrated Magnetism

A Highly Entropic Metallic State K. H. Kim et al. Universal Workshop on Frustrated Magnetism

Praseodymium Crystal Field levels: 116 meV 105 meV 5 K Pr 1.2 Bi 0.8 Ru 2 O 7 85 meV 50 meV 200 K 10 meV 0 Five moves from GS infers it is doublet: International Workshop on Frustrated Magnetism

Fluctuations in metallic Pr 1.2 Bi 0.8 Ru 2 O 7 International Workshop on Frustrated Magnetism

Inhomogeneous Level Splitting Broad Spectrum unaltered Upon warming to Wave vector reliance Follows Pr frame calculate 2 Neutron Scattering measures the level part range International Workshop on Frustrated Magnetism

Inhomogeneous two level framework The level circulation work: Singlet-singlet defenselessness: Sample found the middle value of helplessness Fluctuation-dissemination hypothesis yields International Workshop on Frustrated Magnetism

Data Collapse Confirms "extinguished expanding" International Workshop on Frustrated Magnetism

C(T)/T (J/mole-f.u./K 2 ) C(T)/T (J/mole-f.u./K 2 ) Specific warmth of r ( D )- split doublet International Workshop on Frustrated Magnetism

Susceptibility of r ( D )- split doublet For gapless range low T restricting structure is ~ln T International Workshop on Frustrated Magnetism

Clues to sources of level part T-free appropriation work r (D) Static not rapid marvel Continuous not discrete range Large uncommon deformity or thickness wave delivering conveyance of conditions Same dispersion portrays all x <1.2 Distribution may not originate from Bi doping Magnetic field enters in quadrature Electrostatic not magnetostatic inhomogeneity International Workshop on Frustrated Magnetism

Where else may this happen? Components that can have non-Kramers doublet ground states: Pr 3+ , Pm 3+ , Sm 2+ , Eu 3+ , Tb 3+ , Ho 3+ , Tm 3+ , Yb 2+ , and U 4+ Nominally cubic and stoichiometric frameworks may have stealthy level part issue Doping impacts might be controlled by the initiated level part International Workshop on Frustrated Magnetism

Other Materials to Reconsider Tb 2 Ti 2 O 7 : A non requesting magnet with strange low vitality mode Ho 2 Ti 2 O 7 : Long range requested with uncommon thermodynamics YbBiPt: Ultra overwhelming fermion framework with baffling low E mode (Robinson et al (1995). LiHo x Y 1 - x F 4 quantum turn glass. Strain incited level part includes a compelling transverse field Tb x Y 2-x Ti 2 O 7 : Dilution has included impact of killing Tb through level part International Workshop on Frustrated Magnetism

Metal encasing move in R 2 Ir 2 O 7 Yanagishima and Maeno (2001) Nakatsuji et al. Worldwide Workshop on Frustrated Magnetism

Conclusions Ir and Ru pyrochlores offer MIT moves with baffled attraction Y 2 Ru 2 O 7 : "solid coupling" move Spectral weight pushed to limited E reverberation Q-reliance unaffected by requesting Pr x Bi 2-x Ru 2 O 7 : static inhomogeneous conveyance of level splittings Neutrons: "T-autonomous" wide range C(T)/T: expanded Schottky abnormality c (T): conceivable logarithmic difference at low T Watch out for level part in non-Kramers particles, which are "not so much magnets" International Workshop on Frustrated Magnetism

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