STM studies of individual Ti impurity atoms in Sr2RuO4

Barker, Barry; Dutta, Surajit; Lupien, Christian; McEuen, Paul L.; Kikugawa, Naoki; Maeno, Y.; Davis, J. C.

doi:10.1016/s0921-4526(02)02158-0

Cited by 20 publications

(13 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since all of these features are observed at several different tunneling junction resistances, we can exclude the possibility of a tip-induced effect. We note that a similar pseudo-gap [12] and superstructure [12,13] have been reported in Sr 2 RuO 4 . In Sr 2 RuO 4 , however, such a superstructure was observed even at high biasvoltages (up to -750 mV), indicating a complete reconstruction of atomic position [13].…”

supporting

confidence: 85%

Local Tunneling Spectroscopy across a Metamagnetic Critical Point in the Bilayer RuthenateSr3Ru2O7

et al. 2007

View full text Add to dashboard Cite

The local spectroscopic signatures of metamagnetic criticality in Sr3Ru2O7 were explored using scanning tunneling microscopy (STM). Singular features in the tunneling spectrum were found close to the Fermi level, as would be expected in a Stoner picture of itinerant electron metamagnetism. These features showed a pronounced magnetic field dependence across the metamagnetic critical point, which cannot be understood in terms of a naive Stoner theory. In addition, a pseudo-gap structure was observed over several tens of meV, accompanied by a c(2 × 2) superstructure in STM images. This result represents a new electronic ordering at the surface in the absence of any measurable surface reconstruction.PACS numbers: 68.37. Ef, 71.27.+a, 75.30.Kz The subtle interplay between spin, charge and orbital degrees of freedom in strongly correlated electron systems gives rise to a wide variety of competing electronic phases [1]. A variety of exotic properties have been reported as a result of this competition between different forms of order, and the associated (quantum) critical behavior. Recently, the bi-layer ruthenate Sr 3 Ru 2 O 7 , n = 2 member of the Ruddlesden-Popper series Sr n+1 Ru n O 3n+1 , has attracted considerable interest because of its criticalities. In dimensionality, Sr 3 Ru 2 O 7 is intermediate between the n = 1 compound Sr 2 RuO 4 , a spin triplet superconductor [2], and the n = ∞ system SrRuO 3 , an itinerant ferromagnet [3]. In common with other Sr n+1 Ru n O 3n+1 compounds, four 4d-electrons are accommodated in its almost triply degenerate t 2g orbitals, implying that orbital degrees of freedom are likely to play an important role.The ground state of Sr 3 Ru 2 O 7 is a (paramagnetic) Fermi liquid. However, the effective mass of the conduction electrons is greatly enhanced, and there is strong evidence of underlying criticality towards electronically and magnetically ordered states. The magnetic susceptibility shows a well-defined peak at T ∼ 16 K, and its large value in the limit T → 0 suggests a substantial Stoner enhancement [4]. These results indicate that the system is very close to a ferromagnetic instability. Indeed, a weakly first-order metamagnetic phase transition occurs in an applied magnetic field of 5.5 T for B//ab, and 8 T for B//c [5,6]. Furthermore, at only 5% doping of Mn impurities on Ru sites, the system becomes an antiferromagnetic insulator and is believed to exhibit orbital ordering [7].The criticalities should manifest themselves as anomalies in low energy spin and charge excitations. The existence of low-lying ferromagnetic spin fluctuations near the metamagnetic critical point has been confirmed by NMR [8]. Similarly, quasi-particle mass anomalies have been observed in de Haas van Alphen (dHvA) measurements at the critical point [9]. However, until now, no spectroscopic data spanning the transition have been available. Given that criticality is well defined only for temperatures of a few K, meV (or better) resolution is necessary to capture the spectroscopic signatures of crit...

show abstract

supporting

confidence: 85%

Local Tunneling Spectroscopy across a Metamagnetic Critical Point in the Bilayer RuthenateSr3Ru2O7

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Therefore we conclude that Sr 2 RuO 4 cleaves preferentially between the SrO planes regardless of the cleaving temperature, and that the maximum in the modulation we see in the STM image is occurring directly above the Sr atoms. As a final note, it has been found in an STM study of Sr 2 ðTi Àx Ru 1Àx ÞO 4 that the signature of the Ti substitution appears in between the STM maxima further supporting the idea of a corrugation centered on the Sr atoms [15,25].…”

mentioning

confidence: 64%

“…As a final note, it has been found in an STM study of Sr 2 (Ti −x Ru 1−x )O 4 that the signature of the Ti substitution appears in between the STM maxima further supporting the idea of a corrugation centered on the Sr atoms. 14,25 The different surface properties seen in ARPES 9,15 and in STM 14 could also be caused by different surface reconstructions. Using LEED, we found extra peaks associated with a √ 2 × √ 2 reconstruction (not shown), as discussed previously by Matzdorf et al.…”

mentioning

confidence: 99%

Cleaving-Temperature Dependence of Layered-Oxide Surfaces

et al. 2008

View full text Add to dashboard Cite

The surfaces generated by cleaving nonpolar, two-dimensional oxides are often considered to be perfect or ideal. However, single particle spectroscopies on Sr2RuO4, an archetypal nonpolar two-dimensional oxide, show significant cleavage temperature dependence. We demonstrate that this is not a consequence of the intrinsic characteristics of the surface: lattice parameters and symmetries, step heights, atom positions, or density of states. Instead, we find a marked increase in the density of defects at the mesoscopic scale with increased cleave temperature. The potential generality of these defects to oxide surfaces may have broad consequences to interfacial control and the interpretation of surface sensitive measurements.

show abstract

“…In the following we illustrate our results on the specific case of Mn-doped MgB 2 , but we wish to emphasize that much of our discussions carry over to other systems as well 10 , and that our conclusions are rather general. There are several reasons to choose the Mn − MgB 2 system.…”

Section: Introductionmentioning

confidence: 86%

Spin-resolved spectra of Shiba multiplets from Mn impurities inMgB2

et al. 2008

View full text Add to dashboard Cite

We study the effect of magnetic Mn ions on the two-band superconductor MgB 2 , and compute both the total and spin-resolved scanning tunneling spectrum in the vicinity of the magnetic impurity. We show that when the internal structure of the Mn ion's d-shell is taken into account, multiple Shiba states appear in the spectrum. The presence of these multiplets could alter significantly the overall interpretation of local tunneling spectra for a wide range of superconducting hosts and magnetic impurities.

show abstract

STM studies of individual Ti impurity atoms in Sr2RuO4

Cited by 20 publications

References 13 publications

Local Tunneling Spectroscopy across a Metamagnetic Critical Point in the Bilayer RuthenateSr3Ru2O7

Local Tunneling Spectroscopy across a Metamagnetic Critical Point in the Bilayer RuthenateSr3Ru2O7

Cleaving-Temperature Dependence of Layered-Oxide Surfaces

Spin-resolved spectra of Shiba multiplets from Mn impurities inMgB2

Contact Info

Product

Resources

About