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Materials Challenges for Memory

What does gender got to do with science

<center>Louis Stokes Regional Center of Excellence for the Study of STEM Interventions<center>

<CENTER>Translating Critical, Strengths-Based Conceptual Frameworks to STEM Programming Design & Dissemination<CENTER>


 **Sponsored in Partnership by:**
 National Science Foundation, Understanding Interventions, University of Michigan and University of Missouri
 
 
 		
	
Dear Colleagues,

Welcome to the inaugural Louis Stokes Regional Center of Excellence for the Study of STEM Interventions ‎‎(LSCRE ‎‎‎‎SOSI) Summer Institute. SOSI is an NSF funded initiative that reflects a collaboration of STEM and STEM Education Scholars ‎and Program Administrators from the University of Missouri-Columbia, Understanding ‎Interventions, Inc., and the University of Michigan.‎ We offer training and development for STEM program administrators, faculty, and other ‎stakeholders ‎in critical, strengths-based theories and evidence-based practices. Key to our work is providing the tools and avenues for our participants to inform their practice and contribute to the body of translational research that facilitate ‎underrepresented students’ success in STEM. Beyond the Summer Institutes, SOSI, through the Understanding Interventions Index, supports resources for access to the STEM research-to-practice translational literature, a database of journals that publish these works, relevant published measures, and the Understanding Interventions Journal as an outlet for dissemination. This work also extends to webinars and workshops held throughout the year as an integral part of the collaboration between SOSI and its partners. 

This 2021 Summer Institute is designed to address participant needs across a range of experience in our concurrent sessions. Concurrent Sessions 1 are tailored for those of us who have professional training outside the social and behavioral sciences but are looking to develop proficiency, scholarship, and utilize methodologies that test theories like Community Cultural Wealth (CCW), Phenomenological Variant of Ecological Systems Theory (PVEST) and Social Cognitive Career Theory (SCCT). Concurrent Sessions 2 are tailored to those with some experience in these areas and are looking to engage more deeply. Some sessions like those that address measures, implementation, and outcomes will be joint. For the current topic sessions, participants will not be limited a specific concurrent session but will have the flexibility to attend the session that they feel most appropriate to their level of experience. 

We look forward to an exciting and productive institute as we all leverage our varied experiences, perspectives, and ideas to this growing community of practice. We would also like to extend our deep gratitude to the National Science Foundation for its generous support of this work.


Best,

SOSI Leadership Team

SOSI Virtual Summer Institute 2021

technical paper


![](https://assets.underline.io/uploads/markdown_image/1/image/2e10c515564e9ec3287ee4c664011c20.png)

The energy cost of storing and moving data is enormous, and is growing at such a rapid pace that within a few years the power demand may overwhelm some developed nations. Non-volatile memory (NVM) and neuromorphic computing are enabling critical advances in this area, but there are many scientific and technological challenges. This conference will cover the materials challenges of different memory technologies, from the fundamental processes and mechanisms, to industry perspectives on materials specifications and manufacturing.

Phase change memory devices for electrical and optical in-memory computing

Operando methods for determining lithiation, switching-mechanisms and phase changes in electrochemical processes

Material challenges in ferroelectric memories

Devices and materials for in-memory computing: challenges and opportunities

Industry challenges and outlook for resistive memories

Resistive +PCM

Spin-transfer-torque MRAM

Oxide perovskites have received widespread attention ever since their discovery due to the multiple physical properties they exhibit, including ferroelectricity, multiferroicity, and superconductivity. One prominent absence in this list of properties that oxide perovskites exhibit is electronic topological order. This is a consequence of the large band gaps of oxide perovskites, which make the band inversions necessary for topology impossible. Alternatively, we find that topological phonons – nodal rings, nodal lines, and Weyl points – are ubiquitous in oxide perovskites in terms of structures (tetragonal, orthorhombic, and rhombohedral), compounds (BaTiO3, PbTiO3, and SrTiO3), and external conditions (photoexcitation, strain, and temperature). In particular, in the tetragonal phase of these compounds all types of topological phonons can simultaneously emerge when stabilized by photoexcitation, whereas the tetragonal phase stabilized by thermal fluctuations only hosts a more limited set of topological phonon states. In addition, we find that the photoexcited carrier density can be used to control the emergent topological states, for example driving the creation/annihilation of Weyl points and switching between nodal lines and nodal rings. Overall, we propose oxide perovskites as a versatile platform in which to study topological phonons and their manipulation with light [1]. Topological phonons in oxide perovskites provide a promising platform to study physical phenomena, ranging from the phonon Hall effect to superconductivity, and may also offer new technological opportunities such as the realization of controllable topological quantum states for neuromorphic computing.

Reference:
[1] Bo Peng, Yuchen Hu, Shuichi Murakami, Tiantian Zhang, Bartomeu Monserrat. Topological phonons in oxide perovskites controlled by light. Science Advances 6 (46), eabd1618 (2020).

Topological phonons in oxide perovskites controlled by light

Magneto-ionics, understood as voltage-driven ion transport in magnetic materials, could represent a significant breakthrough in the search for routes to enhance energy efficiency in magnetically-actuated devices. Particularly, magneto-ionics in Co3O4 allows for voltage-controlled ON−OFF ferromagnetism, since Co3O4 (paramagnetic) can be partially reduced to Co (ferromagnetic) by voltage actuation and reversed by applying a voltage of opposite polarity [1]. This could be used to binary encode information: for example, OFF = 0 (paramagnetism) and ON = 1 (ferromagnetism). However, ion motion at room temperature is still too slow for applications. The way to apply electric field (voltage actuation) can have a strong impact on the room temperature magneto-ionic motion. Specifically, in electrolyte-gated paramagnetic Co3O4 films, the oxygen magneto-ionic motion can be increased by more than one order of magnitude by applying the electric field through an electrochemical capacitor configuration (i.e., using, as working electrode, an underlying conducting buffer layer beneath the Co3O4 film) rather than using an electric-double-layer transistor-like configuration (i.e., placing the electric contact at one side of the Co3O4 film as working electrode). This is due to a greater uniformity and strength of the electric field in the capacitor design [1,2].

[1] A. Quintana, E. Menéndez, M. O. Liedke, M. Butterling, A. Wagner, V. Sireus, P. Torruella, S. Estradé, F. Peiró, J. Dendooven, C. Detavernier, P. D. Murray, D. A. Gilbert, K. Liu, E. Pellicer, J. Nogues and J. Sort, Voltage-controlled ON−OFF ferromagnetism at room temperature in a single metal oxide film, ACS Nano 12 (2018) 10291–10300
[2] J. de Rojas, A. Quintana, A. Lopeandía, J. Salguero, J. L. Costa-Krämer, L. Abad, M. O. Liedke, M. Butterling, A. Wagner, L. Henderick, J. Dendooven, C. Detavernier, J. Sort and E. Menéndez, Boosting room-temperature magneto-ionics in a non-magnetic oxide semiconductor, Advanced Functional Materials 30 (2020) 2003704

ON-OFF magneto-ionics in Co3O4

Layered magnetic semiconductors are a key resource for next-generation spintronic logic and memory applications [1]. The recent advances in growing 2D magnetic materials provide ease of thickness control, atomistic mechanical stability, measurable spin-mobility, and a practical approach for spintronic research [2]. Here, we have synthesized 2D chromium sulfide (Cr2S3) using chemical vapor deposition (CVD) on a sapphire substrate and carried out transport measurements under an external magnetic field applied out-of-plane (Figure 1). The microscopy and Raman investigations suggest layered non-van der Waal crystal growth along the c-axis (001) direction. The set of investigations suggest that the 2D-Cr2S3 consists of a layered geometry with magnetic behavior similar to that reported in CrI3 [3] i.e., intra-layer ferromagnetic and inter-layer antiferromagnetic ordering along the stacking (c-axis) direction. The Neil temperature (TN) is noted as ~120 K and small magnetic contributions are evident till room temperature (300 K) as shown in Figures 1d and 2a. 
A four-probe device structure with non-magnetic (Al) electrodes was fabricated using standard semiconductor processing[4] to carry out the transport measurements as shown in Fig. 1c. The voltage across the two inner electrodes was measured in response to a constant current of 10 µA injected into the device. The field-induced magnetoresistance (MRH) was calculated as 〖MR〗_H=(R(H)-R(0))/(R(0)), where R(H) is the resistance measured at an applied magnetic field strength of H in Oe. A large MRH of -25% was observed at 100 K, i.e., near TN. Our study shows the change in MRH magnitude from negative to positive below 20 K as shown in Figure 2a. 
To probe the spin induced magnetoresistance (MR_s=(∆R_s)/R_0 where ∆R_s is the difference in resistance between the positive sweep and the negative sweep of the applied magnetic field, as shown in Figure 2b), the resistance versus a dual sweep (0→5T→0→-5T→0→5T) of the magnetic field (Hext), has been investigated at different temperatures. For TN<T≤300 K, a small negative MRs vs. Hext was noticed. This behavior is characteristic of a disordered magnetic state, typically attributed to quenching of spin disorder upon applying a Hext [5]. On the other hand, distinct resistance states (0 and 1) are observed with Rs ≅ 3 kΩ when cooled down to 10 K at ±5 kOe and 10 µA (power = 0.2 watts). Here, MRs of 13% is observed, which has not been shown before in thin-film Cr2S3 systems. The large resistance hysteresis also matches the magnetization hysteresis (not shown here) and can be attributed to the large (2-5 x 108) spins/m3, which get flipped above the threshold magnetic field.[6]
In summary, we have successfully demonstrated the magneto-resistive effect in CVD-grown 2D Cr2S3 thin film, which makes Cr-based 2D materials novel among 2D materials. Furthermore, these Cr2S3 with ferrimagnetic and narrow bandgap characteristics provide an excellent platform for next-generation spintronic applications.

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