About

Dr. Nasim Alem is a Professor of Materials Science and Engineering at Penn State University, affiliated with the Department of Materials Science and Engineering and the Penn State Intercollege Graduate Degree Program in Materials Science and Engineering. She received her B.S. degree in Metallurgical Engineering from Sharif University of Technology in Tehran, Iran, her M.S. in Materials Science and Engineering from Worcester Polytechnic Institute, and completed her Ph.D. in Materials Science and Engineering at Northwestern University in 2008. Her research has focused on the nanoscale mechanics and deformation behavior of confined interphases in multilayered metal-ceramic systems, utilizing transmission electron microscopy to investigate the role of chemistry and size scale on plasticity and deformation mechanisms. During her postdoctoral work at the University of California Berkeley and Lawrence Berkeley National Lab, she studied the atomic structure of defects and edges in two-dimensional crystals such as graphene and hexagonal boron nitride, exploring defect formation, growth, and dynamics under various conditions. Her current research centers on understanding how atomic and chemical structures of defects, vacancies, interfaces, and grain boundaries influence the physical, chemical, and electronic properties of crystals, particularly in applications related to energy and catalysis. She employs imaging and spectroscopy techniques in transmission electron microscopy to probe these features and their evolution under thermal and electrical loading, aiming to tailor materials properties for functional device applications.

Research topics

• Nanotechnology
• Materials science
• Chemistry
• Condensed matter physics
• Optoelectronics
• Physics
• Optics
• Chemical physics
• Composite material
• Quantum mechanics
• Crystallography
• Particle physics
• Metallurgy
• Computational chemistry

Selected publications

• Giant room temperature anomalous Hall effect and tunable topology in a ferromagnetic topological semimetal Co2MnAl

  Nature Communications · 201 citations

  • Condensed matter physics
  • Physics
  • Quantum mechanics

  Abstract Weyl semimetals exhibit unusual surface states and anomalous transport phenomena. It is hard to manipulate the band structure topology of specific Weyl materials. Topological transport phenomena usually appear at very low temperatures, which sets challenges for applications. In this work, we demonstrate the band topology modification via a weak magnetic field in a ferromagnetic Weyl semimetal candidate, Co2MnAl, at room temperature. We observe a tunable, giant anomalous Hall effect (AHE) induced by the transition involving Weyl points and nodal rings. The AHE conductivity is as large as that of a 3D quantum AHE, with the Hall angle (ΘH) reaching a record value ( $$\tan {\Theta }^{H}=0.21$$ tan Θ H = 0.21 ) at the room temperature among magnetic conductors. Furthermore, we propose a material recipe to generate large AHE by gaping nodal rings without requiring Weyl points. Our work reveals an intrinsically magnetic platform to explore the interplay between magnetic dynamics and topological physics for developing spintronic devices.

  DOI

• Cryogenic Focused Ion Beam Preparation of Organic-Inorganic Hybrid Perovskite FAPbI3 for Transmission Electron Microscopy

  Microscopy and Microanalysis · 2025-07-01

  articleSenior author
  PublisherDOI

• Probing Nanoscale Vibrational Properties in Monoclinic Beta Gallium Oxide via Vibrational EELS

  Microscopy and Microanalysis · 2025-07-01

  articleSenior author
  PublisherDOI

• Chemically‐Disordered Transparent Conductive Perovskites With High Crystalline Fidelity (Adv. Sci. 42/2025)

  Advanced Science · 2025-11-01 · 2 citations

  articleOpen access
  PublisherOA PDFDOI

• Growth of InBi on InSb(100) via molecular beam epitaxy

  Journal of Vacuum Science & Technology A Vacuum Surfaces and Films · 2025-04-11 · 2 citations

  article

  Binary bismides (AlBi, GaBi, and InBi) are materials that are a part of the familiar III–V material class but have properties that are distinct from the typical nitrides, phosphides, arsenides, and antimonides. Specifically, binary bismides are all predicted to be topologically nontrivial materials that can take on the zinc-blende crystal structure. In addition, these materials all have narrow bandgaps that are suitable for mid-infrared optoelectronics. Successful growth of single-crystalline zinc-blende bismide films has the potential to revolutionize midwave and long-wave infrared devices as well as add topologically nontrivial materials to the III–V family. Here, we present the growth of InBi on InSb(100) substrates using molecular beam epitaxy and characterization of these films using x-ray diffraction and scanning electron microscopy. Additionally, we report attempts at the growth of GaBi on InSb(100) substrates and characterization of these films using x-ray diffraction and transmission electron microscopy. This work demonstrates the growth of InBi on InSb(100) substrates, providing further insight into the bismide material system.

  PublisherDOI

• Discovery of a layered multiferroic compound Cu _{1− <i>x</i>} Mn _{1+ <i>y</i>} SiTe ₃ with strong magnetoelectric coupling

  Science Advances · 2025-01-01 · 6 citations

  articleOpen access

  Multiferroic materials host both ferroelectricity and magnetism, offering potential for magnetic memory and spin transistor applications. Here, we report a multiferroic chalcogenide semiconductor Cu 1−x Mn 1+y SiTe 3 (0.04 ≤ x ≤ 0.26; 0.03 ≤ y ≤ 0.15), which crystallizes in a polar monoclinic structure ( Pm space group). It exhibits a canted antiferromagnetic state below 35 kelvin, with magnetic hysteresis and remanent magnetization under 15 kelvin. We demonstrate multiferroicity and strong magnetoelectric coupling through magnetodielectric and magnetocurrent measurements. At 10 kelvin, the magnetically induced electric polarization reaches ~0.8 microcoulombs per square centimeter, comparable to the highest value in oxide multiferroics. We also observe possible room-temperature ferroelectricity. Given that multiferroicity is very rare among transition metal chalcogenides, our finding sets up a unique materials platform for designing multiferroic chalcogenides.

  PublisherDOI

• Resolving Structural Transitions in Lanthanide High-Entropy Oxides

  ArXiv.org · 2025-12-03

  preprintOpen access

  We report a temperature-composition phase diagram for the chemically disordered and CeO2-LA2O3 high entropy oxides (HEOs), where LA denotes equimolar Y, La, Sm, and Pr, delineating stability regions for bixbyite, disordered fluorite, and intermediate vacancy-ordered fluorite phases. The diagram is constructed from a characterization package applied to bulk ceramics including X-ray diffraction (XRD), transmission electron microscopy (TEM) electron diffraction, Raman spectroscopy, energy-dispersive spectroscopy, X-ray absorption near-edge structure spectroscopy, and ultraviolet-visible spectroscopy, to quantify crystal structure at multiple length-scales, local coordination environments, and electronic structures across the formulation space. This comprehensive measurement suite is critical to identify boundaries between the closely related phases. For example, Raman scattering reveals local structural and defect environments unique to bixbyite local order that persist to ~50% Ce under equilibrium synthesis conditions but are invisible to XRD and TEM. We also report a companion thin film study to demonstrate that quenched kinetic energy from a physical deposition process can metastabilize the high symmetry, and thus high entropy, fluorite phase with only 20% Ce. This is noteworthy because electroneutrality constraints demand an exceptionally vacated oxygen sublattice; we estimate 16.7%, approaching that of delta-Bi2O3. Together, our equilibrium ceramics and far-from-equilibrium thin films show that when synthesis is coupled with rigorously chosen, multi-length-scale characterization, now one can identify the phase stability thermodynamic drivers and simultaneously derive practical guidelines for experimentally realizing targeted phases and structures - and thereby deliberately engineer properties in CeO2-LA2O3 HEOs, whose broad defect chemistries demand such an approach.

  PublisherOA PDFDOI

• Comparison of the MOCVD growth and properties of wafer-scale transition metal dichalcogenide epitaxial monolayers

  2D Materials · 2025-07-29 · 8 citations

  articleOpen accessCorresponding

  Abstract Epitaxial growth of transition metal dichalcogenides (TMDs) by metalorganic chemical vapor deposition is a promising method for wafer-scale synthesis of monolayer films. This study focuses on a comparison of the epitaxial growth of MoS 2 , WS 2 , and WSe 2 monolayers on 2 inch c-plane sapphire substrates using a cold-wall reactor with metal hexacarbonyl and hydride chalcogen sources. Uniform thermofluidic conditions enabled a comparative analysis of nucleation density, domain size, and lateral growth rate across TMD compounds, shedding light on the impact of TMD chemistry on epitaxial growth. Despite the use of chemically analogous precursors such as Mo(CO) 6 or W(CO) 6 and H 2 S or H 2 Se, significant differences in growth behavior are observed. Comprehensive structural, optical, and transport characterizations provide insights into sulfur versus selenium-based TMDs, advancing the understanding of optimized growth conditions for these emerging materials.

  PublisherDOI

• Thermodynamics-inspired high-entropy oxide synthesis

  Nature Communications · 2025-09-02 · 22 citations

  articleOpen access

  High-entropy oxide (HEO) thermodynamics transcend temperature-centric approaches, spanning a multidimensional landscape where oxygen chemical potential plays a decisive role. Here, we experimentally demonstrate how controlling the oxygen chemical potential coerces multivalent cations into divalent states in rock salt HEOs. We construct a preferred valence phase diagram based on thermodynamic stability and equilibrium analysis, alongside a high throughput enthalpic stability map derived from atomistic calculations leveraging machine learning interatomic potentials. We identify and synthesize seven equimolar, single-phase rock salt compositions incorporating Mn, Fe, or both, as confirmed by X-ray diffraction and fluorescence. Energy-dispersive X-ray spectroscopy confirms homogeneous cation distribution, whereas X-ray absorption fine structure analysis reveals predominantly divalent Mn and Fe states, despite their inherent multivalent tendencies. Ultimately, we introduce oxygen chemical potential overlap as a key complementary descriptor for predicting HEO stability and synthesizability. Although we focus on rock salt HEOs, our methods are chemically and structurally agnostic, providing a broadly adaptable framework for navigating HEOs thermodynamics and enabling a broader compositional range with contemporary property interest.

  PublisherOA PDFDOI

• Chemically‐Disordered Transparent Conductive Perovskites With High Crystalline Fidelity

  Advanced Science · 2025-07-12 · 7 citations

  preprintOpen access

  Abstract This manuscript presents a working model linking chemical disorder and transport properties in correlated‐electron perovskites with high‐entropy formulations and a framework to actively design them. This work demonstrates this new learning in epitaxial Sr x (Ti,Cr,Nb,Mo,W)O 3 thin films that exhibit exceptional crystalline fidelity despite a diverse chemical formulation where most B ‐site species are highly misfit with respect to valence and radius. X‐ray diffraction, X‐ray photoelectron spectroscopy, and transmission electron microscopy confirm a unique combination of chemical disorder and structural perfection in thin and thick epitaxial layers. This combination produces an optical transparency window that surpasses that of the constituent end‐members in the UV and IR, while maintaining relatively low electrical resistivity. This work addresses the computational challenges of modeling such systems and investigate short‐range ordering using cluster expansion. These results showcase that unusual d ‐metal combinations access an expanded property design space that is predictable using end‐member characteristics and their interactions – though unavailable to them – thus offering performance advances in optical, high‐frequency, spintronic, and quantum devices.

  PublisherOA PDFDOI

Recent grants

• CAREER: Structurally and Chemically Ordered States in Low Dimensional Crystals

  NSF · $520k · 2017–2023

Frequent coauthors

• Leixin Miao

  Pennsylvania State University

  59 shared

• Alex Zettl

  Kavli Energy NanoScience Institute

  55 shared

• Saiphaneendra Bachu

  Pennsylvania State University

  37 shared

• Joan M. Redwing

  Pennsylvania State University

  32 shared

• Venkatraman Gopalan

  26 shared

• Danielle Reifsnyder Hickey

  25 shared

• Parivash Moradifar

  25 shared

• Zhiqiang Mao

  Pennsylvania State University

  23 shared

Awards & honors

• Taylor Lecture
• Tressler Lecture
• McFarland Award