Nuclear spin-lattice relaxation in narrow gap semiconductors TiPtSn and ZrPtSn

Grykałowska, A.; Nowak, B.

doi:10.1016/j.intermet.2007.05.009

Cited by 9 publications

(11 citation statements)

References 16 publications

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“…We stress that the observed low-temperature 1/ T 1 T clearly rules out the possibility that for this loading range the system can be discussed as a narrow-gap semiconductor. In this case, 1/ T 1 T would be dominated by the exp(−Δ/ k B T ) term for , which decays exponentially with decreasing temperature 24 , in disagreement with the experimental data.…”

Section: Resultsmentioning

confidence: 52%

Metal-to-insulator crossover in alkali doped zeolite

Igarashi

Jeglič

Krajnc

et al. 2016

Sci Rep

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We report a systematic nuclear magnetic resonance investigation of the 23Na spin-lattice relaxation rate, 1/T1, in sodium loaded low-silica X (LSX) zeolite, Nan/Na12-LSX, for various loading levels of sodium atoms n across the metal-to-insulator crossover. For high loading levels of n ≥ 14.2, 1/T1T shows nearly temperature-independent behaviour between 10 K and 25 K consistent with the Korringa relaxation mechanism and the metallic ground state. As the loading levels decrease below n ≤ 11.6, the extracted density of states (DOS) at the Fermi level sharply decreases, although a residual DOS at Fermi level is still observed even in the samples that lack the metallic Drude-peak in the optical reflectance. The observed crossover is a result of a complex loading-level dependence of electric potential felt by the electrons confined to zeolite cages, where the electronic correlations and disorder both play an important role.

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Section: Resultsmentioning

confidence: 52%

Metal-to-insulator crossover in alkali doped zeolite

Igarashi

Jeglič

Krajnc

et al. 2016

Sci Rep

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“…24 On the other hand, in a standard topologically trivial half-Heusler semiconductor such as TiPtSn, the 195 Pt Knight shifts were found to weakly shift to lower frequencies with increasing temperature (∂K/∂T < 0). 38 From ∂K/∂T > 0 one may conclude that the thermally excited charge carriers in LuPtBi predominantly have s character, with a positive s-hyperfine constant. Evidently, a classical temperature dependence of the NMR shift, K(T) ∝ n H /k B T, does not apply for LuPtBi.…”

Section: Resultsmentioning

confidence: 99%

Band Inversion in Topologically Nontrivial Half-Heusler Bismuthides: ²⁰⁹Bi NMR Study

2015

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209Bi nuclear magnetic resonance (NMR) was measured in half-Heusler bismuthides ScPdBi, LuPdBi, and LuPtBi and discussed in conjunction with the NMR data recently reported for YPdBi and YPtBi. The observed 209Bi NMR spectra exhibit low intensity because of short nuclear transverse relaxation time (T 2) governed by sizable structural disorder. Remarkably, the NMR frequency shifts are positive for topologically trivial ScPdBi and YPdBi, yet strongly negative for topologically nontrivial YPtBi, LuPtBi, and LuPdBi with postulated inversion of the electronic bands near the Fermi level. For the former two compounds, the spin–lattice relaxation rate (1/T 1) is very large and seems correlated with the strength of spin–orbit coupling. The study demonstrates the capability of NMR spectroscopy to probe the band inversion in putative topological insulators.

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“…In Figure 1 inset we plot ( ) versus . A straight line is indicative of a metallic sample, where the quantity ( ) is proportional to the carrier density [17][18][19][20][21][22]. The inset graph shows that the nanocrystals have higher carrier density than the m&p samples across all temperatures investigated.…”

Section: Introductionmentioning

confidence: 99%

“…The Korringa values, T 1• T, were 24 s•K for the m&p sample (below 200 K) and 11 s•K for the nanocrystals (across all temperatures, 140-420 K). These values are not unusual for semiconductors and tend to reflect the fact that T 1 •T is inversely proportional to the square of the electronic density of states (DOS) at the Fermi level, ( ) [16][17][18][19][20][21]. A lower Korringa value means higher carrier density and a more metallic state.…”

Section: Introductionmentioning

confidence: 99%

NMR Probe of Metallic States in Nanoscale Topological Insulators

et al. 2013

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A 125Te NMR study of bismuth telluride nanoparticles as a function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from the single to the bimodal regime. The satellite peak features a negative Knight shift and higher relaxivity, consistent with core polarization from p-band carriers. Whereas nanocrystals follow a Korringa law in the range 140-420 K, micrometer particles do so only below 200 K. The results reveal increased metallicity of these nanoscale topological insulators in the limit of higher surface-to-volume ratios.

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Nuclear spin-lattice relaxation in narrow gap semiconductors TiPtSn and ZrPtSn

Cited by 9 publications

References 16 publications

Metal-to-insulator crossover in alkali doped zeolite

Metal-to-insulator crossover in alkali doped zeolite

Band Inversion in Topologically Nontrivial Half-Heusler Bismuthides: ²⁰⁹Bi NMR Study

NMR Probe of Metallic States in Nanoscale Topological Insulators

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Nuclear spin-lattice relaxation in narrow gap semiconductors TiPtSn and ZrPtSn

Cited by 9 publications

References 16 publications

Metal-to-insulator crossover in alkali doped zeolite

Metal-to-insulator crossover in alkali doped zeolite

Band Inversion in Topologically Nontrivial Half-Heusler Bismuthides: 209Bi NMR Study

NMR Probe of Metallic States in Nanoscale Topological Insulators

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Product

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Band Inversion in Topologically Nontrivial Half-Heusler Bismuthides: ²⁰⁹Bi NMR Study