Competing effects of surface phonon softening and quantum size effects on the superconducting properties of nanostructured Pb.
نویسندگان
چکیده
The superconducting transition temperature (T(C)) in nanostructured Pb decreases from 7.24 to 6.4 K as the particle size is reduced from 65 to 7 nm, below which superconductivity is lost rather abruptly. In contrast, there is a large enhancement in the upper critical field (H(C2)) in the same size regime. We explore the origin of the unusual robustness of T(C) over such a large particle size range in nanostructured Pb by measuring the temperature dependence of the superconducting energy gap in planar tunnel junctions of Al/Al(2)O(3)/nano-Pb. We show that below 22 nm, the electron-phonon coupling strength increases monotonically with decreasing particle size, and almost exactly compensates for the quantum size effect, which is expected to suppress T(C).
منابع مشابه
Surface lattice vibration and electron–phonon interaction in Pb(111) ultrathin superconducting films from first principles: both with and without Si substrate
The lattice vibration and electron–phonon (EP) coupling of three types of Pb ultrathin films were calculated from first principles. For free-standing films, our calculations showed that softening and stiffening of the surface phonons coexist. The obtained EP coupling λ and the superconducting transition temperature TC are smaller than their bulk values. For (1× 1)-Pb/Si(111) films, the obtained...
متن کاملGrain refinement, Microstructural characterization, and tensile properties of die-cast AZ91 alloy via Lead and Tin additions
Effects of different amounts of lead (Pb) and tin (Sn) on microstructure and tensile properties of the AZ91 alloy were studied. The results presented that the microstructure of AZ91 alloy is consisted the α-Mg phase and semi-continuous network of β-Mg17Al12 intermetallics. For the as-cast AZ91 alloy, the average grain siz and the β phase volume fraction were 96.2 µm and of 25.3%, respectively. ...
متن کاملنرم شدگی فونونهای انرژی بالا با گذار عایق - ابررسانا در سیستم ابررسانای Ba1-xKxBiO3
Single crystals of Ba1-xKxBiO3 compound for 0 < x <0.6 from insulator to superconducting region have been grown by electrochemical method. The crystals have been characterized by powder x-ray diffraction and Laue x-ray to determine the crystal structure, formed phases and potassium concentration. Inelastic x-ray scattering spectrum of the crystals has been studied to investigate the phonon pro...
متن کاملModulation Response and Relative Intensity Noise Spectra in Quantum Cascade Lasers
Static properties, relatively intensity noise and intensity modulation response in quantum cascade lasers (QCLs) studied theoretically in this paper. The present rate equations model consists of three equations for the electrons density in the conduction band and one equation for photons density in cavity length. Two equations were derived to calculate the noise and modulation response. Calcula...
متن کاملQuantum Size Effects in Ultrathin Metallic Islands: a Scanning Tunneling Microscopy/Spectroscopy Study
This thesis reports measurements concerning quantum size effects of single crystalline metallic islands by using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Different sample systems are presented in the following chapters. In chapter 2, several aspects of quantum well states (QWS) of Pb ultrathin islands grown on Si(111) substrate are reported. The differential c...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of physics. Condensed matter : an Institute of Physics journal
دوره 21 20 شماره
صفحات -
تاریخ انتشار 2009