scispace - formally typeset
Search or ask a question
Author

Mildred S. Dresselhaus

Bio: Mildred S. Dresselhaus is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Carbon nanotube & Raman spectroscopy. The author has an hindex of 136, co-authored 762 publications receiving 112525 citations. Previous affiliations of Mildred S. Dresselhaus include University of California, Los Angeles & Universidade Federal de Minas Gerais.


Papers
More filters
Journal ArticleDOI
TL;DR: The results suggest that the nanostructures of Kondo insulators can be designed for high performance thermoelectric cooling devices at low temperatures.
Abstract: We predict a large thermoelectric figure-of-merit in Kondo insulator nanowires at low temperatures. The high ZT values are due to the Kondo effect for electrons and boundary scattering on phonons. We simulated the electron properties of the bulk Kondo insulators within the framework of dynamical mean field theory and found that electrons have short mean free path. In nanowire structures, electron transport is hardly affected by the boundary scattering due to their small intrinsic mean free paths while phonons are strongly scattered due to classical size effect. The results suggest that the nanostructures of Kondo insulators can be designed for high performance thermoelectric cooling devices at low temperatures.

37 citations

Journal ArticleDOI
TL;DR: A quantitative description of the electronic magnetic levels of bismuth in the low-quantum number limit is presented in this paper, which is based on the simplifications to the Baraff Hamiltonian made by Maltz and Dresselhaus and includes the effects of bands outside the two-band model.
Abstract: A quantitative description of the electronic magnetic levels of bismuth in the low-quantum-number limit is presented The model is based on the simplifications to the Baraff Hamiltonian made by Maltz and Dresselhaus and includes the effects of bands outside the two-band model as well as the interaction between the $j=0$ levels in the conduction and valence bands represented by a coupling parameter $P$ Magnetoreflection results on interband Landau-level and cyclotron-resonance transitions in the low-quantum-number limit are utilized in the determination of the parameters of this model, including the first quantitatitive measurement of $P$ Values for the direct energy gap, cyclotron effective masses, and coupling parameter $P$ are reported for $\stackrel{\ensuremath{\rightarrow}}{H}\ensuremath{\parallel}\mathrm{binary}$ and $\stackrel{\ensuremath{\rightarrow}}{H}\ensuremath{\parallel}\mathrm{bisectrix}$ axes in the temperature range $42lTl75$ K

37 citations

Journal ArticleDOI
TL;DR: An extremely efficient method for growing pure and highly crystalline CNTs using natural resources: garnet powder as a catalyst, and city gas as a carbon source, which is very promising for providing lowcost, high-quality industrially available CNT products for developing large-scale applications in the near future.
Abstract: The mass production of carbon nanotubes (CNTs) at low cost remains an important technological challenge if applications of CNTs are to be exploited further. Here, we report an extremely efficient method for growing pure and highly crystalline CNTs using natural resources: garnet powder as a catalyst, and city gas as a carbon source. The chemically reduced iron particles on the surface of the sand granules catalyze the decomposition of city gas, leading effectively to a high growth rate of CNTs. This novel method is very promising for providing lowcost, high-quality industrially available CNT products for developing large-scale applications in the near future. To produce CNTs in bulk quantities, a well-developed ironbased catalytic chemical vapor deposition (CCVD) method has been commonly used, as established by one of us after obtaining ultrathin hollow CNTs grown on nanosized iron particles. 2] However, for the production of CNTs, the catalyst is considered as one of the most expensive components. Therefore, to find an alternative cheap and effective catalyst for producing highquality and high-quantity CNTs remains a challenge for the bulk production of this key material in nanotechnology. Recently, Su and Chen reported the preparation of CNTs grown on lava rocks. However, those CNTs did not exhibit a well-ordered structure. In addition, the lava is not easy to handle in the CCVD process. Interestingly, one of us reported early on that the origin of the nanosized iron catalyst which promoted the production of a large amount of fibrous carbon material was the emery paper that was used for polishing the aluminum or graphite substrate used in the CCVD chamber. Later, it was found that brown emery paper is made of fine garnet powder. From this perspective, we report an alternative, environmentally friendly and efficient method for growing multiwalled carbon nanotubes (MWCNTs) using purely natural resources: stone garnet sand as a catalyst and support, and city gas based natural gas as the carbon source. Garnet powder consists of SiO2, FeO, Fe2O3, and Al2O3, among other things (Figure 1a) and is inexpensive ($1.4kg ). The size of the garnet sand particles is around 200 mm (see inset in Figure 1a). We

37 citations

Journal ArticleDOI
24 Aug 2010-ACS Nano
TL;DR: A review of recent advances in carbon nanotube science and applications is presented in terms of what was learned at the NT10 11th International Conference on the Science and Application of Nanotubes held in Montreal, Canada, June 29-July 2, 2010.
Abstract: A review of recent advances in carbon nanotube science and applications is presented in terms of what was learned at the NT10 11th International Conference on the Science and Application of Nanotubes held in Montreal, Canada, June 29−July 2, 2010.

36 citations

Journal ArticleDOI
04 Dec 2009-Small
TL;DR: It is demonstrated that these metallic corrugated inner tubes can be converted into semiconducting tubes by high-temperature thermal treatment in argon, demonstrating for the first time the versatility of the electronic properties for the coalesced structures.
Abstract: Corrugated carbon nanotubes containing a number of defective carbon rings can be synthesized from the coalescence of C60 encapsulated in SWNTs (peapods). In this letter we show that contrary to common wisdom, the presence of non-hexagonal rings can actually induce metallic behavior. To demonstrate this, we used a combination of photoluminescence studies, Raman spectroscopy, transmission electron microscopy, and first-principle quantum calculations. Furthermore, we demonstrate that these metallic corrugated inner tubes can be converted into semiconducting tubes by high-temperature thermal treatment in argon. This finding demonstrates for the first time the versatility of the electronic properties for the coalesced structures and provides a novel way to tailor them by thermal processing.

36 citations


Cited by
More filters
Journal ArticleDOI
22 Oct 2004-Science
TL;DR: Monocrystalline graphitic films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands and they exhibit a strong ambipolar electric field effect.
Abstract: We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in concentrations up to 10 13 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by applying gate voltage.

55,532 citations

Journal ArticleDOI
Sumio Iijima1
01 Nov 1991-Nature
TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.

39,086 citations

Journal ArticleDOI
TL;DR: Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena can now be mimicked and tested in table-top experiments.
Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

35,293 citations

01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
TL;DR: In this paper, the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations, are discussed.
Abstract: This article reviews the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.

20,824 citations