BNL Home

Meetings & Workshops

  1. MAR

    15

    Thursday

    Condensed-Matter Physics & Materials Science Seminar

    "Enabling emergent spin-orbit magnetism in iridate-based heterostructures"

    Presented by Jian Liu, The University of Tennessee, Knoxville

    11 am, ISB Bldg. 734 Seminar Room 201 (upstairs)

    Thursday, March 15, 2018, 11:00 am

    Hosted by: Mark Dean

    5d transition metal oxides have emerged as a novel playground for some of the most outstanding and challenging problems in condensed matter physics, such as metal-insulator transition and quantum magnetism. In particular, layered iridates hosting square lattices of IrO6 octahedra have drawn significant interests due to the electronic and magnetic analogy with high-Tc cuprates. However, materials of this kind are limited to a few Ruddlesden-Popper (RP) compounds. In this talk, I will discuss our recent work on overcoming this bottleneck by constructing such two-dimensional (2D) structures confined in superlattices grown by heteroepitaxy. By leveraging the layering control of epitaxial growth, we are not only able to develop new structural variants of layered iridates, but also unravel and exploit the intriguing spin-orbit-driven 2D magnetism beyond the cuprate physics yet invisible in the RP iridates. The results demonstrate the power of this approach in tailing the exchange interactions, enabling new magnetic controls, and providing unique insights into the emergent phenomena of 5d electrons.

  2. MAR

    22

    Thursday

    BWIS Lecture

    "Madame Curie's Life and Work"

    Presented by Edward Sierra, BNL Quality Management Office

    4 pm, Large Seminar Room, Bldg. 510

    Thursday, March 22, 2018, 4:00 pm

    Edward Sierra will provide a talk on Marie Curie, an extraordinary scientist, the first woman to win a Nobel Prize, and still the only one awarded with two Nobel Prizes. Ed's interest in the early pioneers of radioactivity was piqued by the discussions he had many years ago with the renowned Dr. Maurice Goldhaber, the prominent physicist and a former Laboratory Director at Brookhaven National Laboratory. He learned that Goldhaber was a student under Sir James Chadwick at the Cavendish Laboratory at Cambridge University and that he attended a graduate course in Berlin given by Dr. Lise Meitner. Ed's research on Meitner led to an interest in Marie Curie. Her work and life is the topic of this talk.

  3. MAY

    14

    Monday

    Condensed-Matter Physics & Materials Science Seminar

    "Superconductivity and quantum paraelectric fluctuations in STO"

    Presented by Alexander Balatsky, Los Alamos National Laboratory

    1:30 pm, ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Monday, May 14, 2018, 1:30 pm

    Hosted by: Laura Classen

    STO is one of the earliest examples of superconductivity in oxides. With the pioneering discovery of the superconductivity in STO interfaces the field of emergent states at interfaces has been rapidly growing. Recently we come to realize that the key to a lot of puzzles in these devices lies in the complicated states of bulk STO[1,2]. Superconducting state is STO exhibits the dome as a function of doping. STO is also a known quantum paraelectric. Historically ferroelectric quantum criticality and superconducting dome in STO were assumed to be unrelated. We propose that they are in fact closely connected. We suggest that ferroelectric quantum criticality can induce superconductivity. We will present our results on investigation of the origin of superconductivity in doped STO using a combination of density functional and strong coupling theory[3]. Our approach suggests a model in which the ferroelectric soft mode fluctuations provide the pairing interaction for superconductivity carriers. This approach adds to the range of superconducting states induced by quantum criticality beyond magnetic and valence fluctuations[3,4,5]. Based on this model we made a prediction that superconducting Tc will increase with increasing 18O isotope substitution, a scenario that is experimentally verifiable[6]. We also discuss proposal to use strain as another tool to control paraelectric fluctuations and thus control superconductivity in STO[7]. We will illustrate the ongoing debate on the nature of the pairing states in bulk STO and in related heterostructure devices: the possibility to realize composite pairing states and multiband superconductivity[8]. [1]J. Haraldsen et al., Phys. Rev. B 84, 020103(R) (2011), [2]J. Haraldsen et al., Phys. Rev. B 85, 134501 (2012), [3]J. Edge et al Phys. Rev. Lett. 115, 247002 (2015), [4] Y. Kedem et.al, Physical Review B 93 , 184507 (2016), [5] CW Rischau et al, Nature Physics, 13, 643–648 (2017) [6] A. Stucky, et.al, Sci