Section 1.1 What are the major goals of the project? (1300c)Complex emergent phenomena in correlated magnetic and electronic systems are generally studied with spatially local approximations like the Local Density Approximation (LDA) and the Dynamical Mean Field Approximation (DMFA). The goal of SD1 is to transform the field by extending these methods to much larger length scales and to validate these approaches with experiment. SD1 is separated into three focus areas, (1) multiscale methods and their experimental validation for correlated materials, (2) multiferroics and unconventional magnets, and (3) unconventional superconductors. The main milestones for year 5 include the development of codes using accelerators (GPU and Intel Phi) in collaboration with CTCI, the development of multiscale codes, the development of experimentally validated computational models for organic magnets, organometallics, and ferroelectric systems using measurements as guide, the improvement of two-particle field theory solvers, and the development of LDA+ methods. Our research agenda continues to evolve as new results and surprising experimental findings lead to new opportunities.

Sections 1.1.1, 1.1.2, and 1.1.3

1.1.1 Major Activities (1300c):

(1) Work (Jarrell, Moreno {LSU}, Marom {Tulane}) includes the development of GW methods, Figs. 1, 2, and a theory for Anderson localization, Fig. 3., the study of superconductivity in a chiral structured compound (DiTusa, Browne {LSU}), Fig. 4, effect of reduced dimensionality in atomically thin layers of Nb3SiTe6 (Mao {Tulane}, Spinu {UNO}), magnetoresistance in Ta2PdSe6, (Mao, Jarrell, Moreno), non-collinear magnetic ordering (Stadler {LSU}), the quantum critical point in Sr2RuO4 (Vekhter {LSU}, Jarrell, Moreno, Mao), transitions in SrVO3 films (Zhang {LSU}), Fig. 5, and response of nanoparticles (Lopata {LSU}).

(2) Activities include investigations of magnonic crystals (Spinu{UNO}), Fig. 6, nanoparticles as MRI contrast agents (Kolesnichenko, Kucheryavy, Goloverda {Xavier}, He, John, Burin {Tulane}, Maharjan, Spinu {UNO}), nanoparticle polymer composites (Chrisey {Tulane}) and, simulations of metallocarborane-containing molecules (Derosa {GSU/LATech}), and stress mediated energy exchange in nanocomposites (Caruntu, Malkinski, Spinu {UNO} and Pesika {Tulane}).

(3) Explorations of unconventional superconductors focused on the pairing state and mechanism, and the role of magnetism (Mao {Tulane}, Spinu {UNO}, Kolesnichenko {Xavier}; Vekhter, Jarrell, Moreno, Jin {LSU}).

1.1.2 Specific Objectives(1300c): The objective of SD1 is to develop a fundamental understanding of the complex phenomena found in correlated and magnetic materials, and multiferroics and to develop related numerical tools with predictive capabilities. The objective of focus 1 is to develop tools that are predictive for correlated materials and may lead to new functionalities. E.g., magnetic semiconductors produce spin polarized currents necessary for spintronics applications or magnetic silicide, germanide, and gallide materials that host novel topologically non-trivial magnetic states which may prove useful for future devices. In focus 2, our work on magnetic materials explores nanoparticles with the objective of finding new strategies for magnetic storage and imaging technologies, while multiferroics have

applications as high-sensitivity ac magnetic field sensors and electrically tunable microwave devices. The objective of focus 3 is to use simulations and experiments to develop a better understanding of unconventional superconductivity. A fuller understanding of these materials is necessary to find superconductors with larger critical temperatures which will enable a host of new devices such as the quantum flux transistor or ultrafast high power switches.

1.1.3 (2000c) Significant Results.

Focus 1, Moreno and Jarrell investigated the controversial Mn valence in GaMnN and demonstrated that it is close to 2+ (d5 ). We incorporated off-diagonal disorder and weak interactions into the Typical Medium Dynamical Cluster Approximation (TMDCA). DiTusa, Shelton, Jarrell, and Moreno have explored the properties of metamagnetic Fe3Ga4 finding a competition between magnetic states that can be tuned via antisite disorder. Lopata showed that a real-time time-dependent density functional theory approach yields accurate optical band gaps and UV and X-Ray absorption properties of isomorphs of SiO2

without input from experiment (Fig 7). He also developed a classical electrodynamics code capturing the properties of Nobel metal nanoparticles from the ultraviolet to the near infrared (Fig. 8) as well as a real-time time-dependent density functional theory approach to X-ray absorption.

Focus 2, Kolesnichenko , Goloverda, and Burin investigated superparamagetic iron oxide nanoparticles and clusters encapsulated into non-polymeric organic shells as prospective imaging agents for early cancer diagnostics. They modeled the nuclear spin relaxation of hydrogen atoms interacting with the nanoparticles necessary for understanding NMR measurements. Malkinski and collaborators were successful in simultaneously applying ac magnetic and electric fields to excite longitudinal vibrations in the composite multiferroics increasing the magnetic susceptibility by two orders of magnitude.

Focus 3, Jin, Moreno and Jarrell, have discovered that the layered compound Ca10Pt3As8(Fe2As2)5 is superconducting below 30 K when doped on either the Ca or Fe sites. These experiments probe the role of the material between FeAs layers (PtnAs8) in producing superconductivity in the Fe-based superconductors. Mao found that the superconductivity of Sr2RuO4 is much closer to magnetic instabilities (ferromagnetic (FM) and incommensurate antiferromagnetic (AFM)) than previously believed.

1.2.4

1.3 Training (500c)

SD1 trained 14 graduate students, 5 REUs, 7 RETs, 7 undergraduate students, 5 postdocs, and 7 high school students. This included the LA-SiGMA seminar program with 18 external speakers and a high performance and heterogeneous computation training course. Kolesnichenko’s work provided underrepresented minority undergraduate students the opportunity to be involved in novel applied science. This work contributed to the development of a new special topics course titled “Chemistry of Materials”.

1.4 Results disseminated and External Engagement: (1000c)

Burin established a collaboration with Ben Gurion University (Israel) as a distinguished visiting professor. Spinu’s metamaterials work was in collaboration with the Universidad Tecnica Federico Santa Maria, Chile and Oakland University. DiTusa, Mao, Kumar, and Lopata ran the LaSiGMA seminar series that informed the community of recent trends in MS&E, and brought it together through broadcasting to participating institutions. Moreno served as the Local organizer of Nanodays attracting more than 500 participants, and participated in outreach events such as Super Science Saturday 2014 (more than 3,000 participants) and Engineering Day at the Louisiana Art and Science Museum (855 guests). Faculty presented their work at international conferences including: Malkinski at INTERMAG in China; Marom at the Institute for Pure and Applied Mathematics; Derosa at a Gordon conference in Italy; Kolesnichenko and Goliverda at International Symposia in London, Dresden and Mainz.

1.5 What do you plan to do during the next reporting period to accomplish the goals (1000c)?

Moreno and Jarrell are incorporating the SiLK method into NWChem. They will apply their TMDCA method to study localization in real materials. Hyperparallel codes will be ported to NSF heterogeneous (accelerated with GPUs and Intel Phi) national leadership class machines. Vekhter will be exploring interfaces between strongly correlated superconductors using realistic electronic structure models. Browne and DiTusa will be modeling the electronic structure of AuBe in an attempt to understand the subtle phase transitions in this chiral structured superconductor. An experiment/simulation collaboration including Jarrell, Moreno, Vekhter, Kellar, Mao has been established to investigate the effect of doping on Sr2RuO4. Goloverda and Kolesnichenko will be investigating the properties of iron oxide nanoparticles as well as to conjugate them with biomolecules to test their target specificity.

2. Impact:

2.1 Budget 2000c: Impact in the field of MS&E: SD1 research has had considerable impact both in producing new discoveries and in providing new computational tools for the exploration. Jarrell and Moreno have created new computational tools for correlated and disordered systems that are being used by scientists around the globe. They are continuing to have a great impact on the capabilities of computationalists to model complex condensed matter systems. Marom is developing accurate many-body perturbation theory methods that allow reliable predictions of excited state properties in organic semiconductors that are crucial for the performance of devices such as polymer-based solar cells. Burin’s work on energy transport in polymers is important for modern nano-technology involving the development of nanodevices. This research is also fundamentally important for understanding of the energy relaxation in chemical reactions. The research of SD1 collaborations is also expected to have an impact on the field of superconductivity. The work of Mao and Spinu has impacted the understanding of superconducting pairing in Fe-based superconductors. Jin, Jarrell and Moreno, investigated Ca10PtnAs8((Fe1-xPtx)2As2)5 which is unique among Fe-based superconductors because of the PtnAs8 layer is crucial for understanding the structure-property relationship of these materials. In addition, Mao’s work combined with Vekhter, Jarrell, and Moreno theoretical work on Sr2RuO4 highlights the role of competing FM/AFM fluctuations in determining its superconducting properties. Vekhter’s calculations suggest new sources of entangled light and for transferring solid state coherence to optical properties which is of intense interest to quantum optics/cryptography. Spinu’s work on thin-film FM/AFM

multilayer systems could serve as spin-valve based sensors for hard disks and microwave devices, while the work led by DiTusa opens new insights on the transport and magnetic properties of magnetic semiconductors.

2.2 Impacts on other fields. The wide range of projects that fall under the SD1 focus areas strive to impact an extensive range of technologically relevant fields. Much of the impact of SD1 projects lies on the arena of creating a future generation of device materials. This is true of the projects exploring the unconventional superconductivity found in cuprates and Fe-pnictides and chalcognides and those focused on magnetism both of which combine experimental, theoretical, and computational efforts. The advances made in SD1 will be influential in the field of spintronics (magnetic semiconductors, nanoscopic magnetic materials, multiferroics) where the goals of producing and manipulating spin-polarized currents with electric fields or light offers possibilities for a new generation of logic and data storage devices. This includes nanoscale magnetic materials which are at the forefront of current research aimed at the development of ultracompact information storage and micro- electronics. In addition, this work aims to make a contribution to biomedical research and diagnostics by way of non-toxic contrast agents that will allow biomolecule and cell tracking. The work involving the characterization and modeling of unconventional superconductors will influence the field of superconducting devices which have the potential to increase the efficiency of the power grid and the speed and efficiency of transportation. These projects also have the possibility of influencing the field of quantum computation through new strategies for quantum entanglement. Finally, several of these projects strive to make advances important to the future of solar energy devices, light emitting arrays, and medical imaging.

2.3 Human Resource development in STEM: SD1 provided support for the research of undergraduate students (including the REU program and support for research during the academic year), high school teachers and students, graduate students, and postdocs. One undergraduate student directed by Mao has been awarded the NSF Graduate Research Fellowship. SD1 provided essential training in the multidisciplinary field of MS&E, as our work lies at the crossroads of physics, chemistry, materials science, and technology. These opportunities were extended to underrepresented groups in STEM fields as well as veterans and served as gateway to STEM careers. Support was provided for several graduate students to attend APS meetings for professional development and networking. Malkinski gave a lecture on micro-origami technology of magnetic films for UNO honor class students.

2.4 Infrastructure: Jarrell took the lead in the LA-SiGMA condo purchase in SuperMike-II. He was also a co-PI on a successful proposal for Shelob, a $500K supercomputer cluster with K20 NVIDIA GPUs, and more recently, SuperMIC, a PetaFLOP cluster accelerated with Intel Phi accelerators. SuperMike-II, Shelob, and SuperMIC are accessible to all LA-SiGMA researchers. The project enabled purchase of multiphysics software COMSOL which enhanced our capability to model physical properties of magnetic and multiferroic microtubes.

2.7 Technology Transfer: Garno has become a consultant for Sonimoto Laboratories (http://www.sonimoto.com/) and provides input for the design and beta testing of designed sample stages for scanning probe microscopy.

2.8 Impact on Society: The results of this project have the possibility of making an impact on socio-economic issues such as Energy and Medicine. Public health and problems related to energy conversion and its environmental and social consequences are main issues in the modern society. We also hope to make an impact on the lives of our students, including undergraduate and high school students who attend our programs, who are trained through the LA-SIGMA program for jobs in materials science. We strive to not only inspire them, but to help prepare for careers in science, engineering and technology and better prepare them to enter the diverse, technologically savvy workforce. In addition, as scientists we hope to make an impact on society in other ways. For example, Garno was served as a scientific diplomat for a Kavli conference in Solo, Indonesia. This event was sponsored by the US State department to work towards improving political connections with scientists and diplomats in Indonesia.

Fig. 1 TiO2 clusters. Vertical ionization potentials (VIP) vs. vertical electron affinity (VEA) for the best ten structures found by three genetic algorithms for all cluster sizes. The loci of constant fundamental gap are indicated by diagonal lines. The presence of several dangling-O atoms is correlated with a high VEA while two dangling-O atoms in proximity to each other are correlated with a low VIP. The electronic properties of TiO2 clusters depend more strongly on the presence of these structural features than on size.

Fig. 2 Heat map representation of the absolute errors with respect to Coupled Cluster Singles and Doubles with perturbative Triples (CCSD(T)) of scGW, scGW0@PBE, G0W0@{COHSEX, HF, PBE, PBEh, LC-ωPBE}, and G0W0+SOSEX@PBE for (a) the Electron affinity (EA) and (b) the Ionization Potential (IP) of the benchmark molecules. G0W0+SOSEX@PBE and G0W0@ LC-ωPBE are the best performers, with the former providing the highest accuracy for EAs and the latter for IPs.

Fig. 3. The evolution of the typical Density of States (TDoS) of the Anderson Hubbard model for increasing values of the Hubbard interaction (U) for the typical medium theory (cluster size Nc=1, (a)) and finite clusters (sizes Nc=12 (b) and 38 (c)) at fixed value of the ratio between the disorder strength and the U-dependent critical disorder =W/Wc

U=0.86 on a log-linear plot for increasing values of the chemical potential . For U=0.0, we show the plot for =0 only, since changing only involves a rigid shift of the TDoS. For U>0, notice the systematic disappearance of the exponential tails (indicated by arrow) and the non-trivial decrease of the TDoS for the finite U (unlike the rigid shift in U=0) as one approaches the mobility edge energy.

Fig. 5: (a) Reflection high-energy electron diffraction (RHEED) intensity oscillation curve during growth of a SrVO3 film grown under substrate temperature of 730~750 C and oxygen pressure of 5x10-7 Torr. The inset panel shows the structural model and diffraction pattern of the film; (c) low energy electron diffraction (LEED) image of a 50 unit cell (u.c.) SVO film, showing a (22)R45 reconstruction on the film surface (electron beam energy = 97.7 eV).

Fig. 4: Simulated Fermi surface of noncentrosymmetric superconductor AuBe (D. A. Browne).

Fig. 6: Comparison between the theoretical (right panel Figs. a, c, and e) and experimental results of broadband microwave absorption spectroscopy on a continuous film (a and b), nanowire arrays with the magnetic field applied parallel to the easy axis (c and d) and nanowire arrays with the magnetic field applied perpendicular to the easy axis (e and f). From the work of Spinu et al.

Fig. 8: Measured and simulated optical absorption of gold/silver core/shell nanoparticles. Our ongoing integrated synthesis, characterization, and classical electrodynamics modeling efforts will accelerate discovery of new broad-wavelength absorbing core/shell and core/shell/shell plasmonic materials for photothermal therapy and molecular sensing.

Fig. 7: We have recently developed techniques for modeling excited state spectra in insulators using a combination of bulk-mimicking clusters and non-Hermitian real-time time-dependent density functional theory (RT-TDDFT). This approach yields properties spanning the visible to X-ray and opens the door to strong-field triggered dynamics simulations and first-principles simulations of nonlinear optical properties.