0000000000999112
AUTHOR
Martin Lee
showing 11 related works from this author
Study of charge density waves in suspended 2H-TaS 2 and 2H-TaSe 2 by nanomechanical resonance
2021
The charge density wave (CDW) state in van der Waals systems shows interesting scaling phenomena as the number of layers can significantly affect the CDW transition temperature, $T_{CDW}$. However, it is often difficult to use conventional methods to study the phase transition in these systems due to their small size and sensitivity to degradation. Degradation is an important parameter which has been shown to greatly influence the superconductivity in layered systems. Since the CDW state competes with the onset of superconductivity, it is expected that $T_{CDW}$ will also be affected by the degradation. Here, we probe the CDW phase transition by the mechanical resonances of suspended 2H-TaS…
Chemical Design and Magnetic Ordering in Thin Layers of 2D Metal–Organic Frameworks (MOFs)
2021
Through rational chemical design, and thanks to the hybrid nature of metal−organic frameworks (MOFs), it is possible to prepare molecule-based 2D magnetic materials stable at ambient conditions. Here, we illustrate the versatility of this approach by changing both the metallic nodes and the ligands in a family of layered MOFs that allows the tuning of their magnetic properties. Specifically, the reaction of benzimidazole-type ligands with different metal centers (MII = Fe, Co, Mn, Zn) in a solventfree synthesis produces a family of crystalline materials, denoted as MUV-1(M), which order antiferromagnetically with critical temperatures that depend on M. Furthermore, the incorporation o…
Nanomechanical probing and strain tuning of the Curie temperature in suspended Cr2Ge2Te6-based heterostructures
2022
AbstractTwo-dimensional magnetic materials with strong magnetostriction are attractive systems for realizing strain-tuning of the magnetization in spintronic and nanomagnetic devices. This requires an understanding of the magneto-mechanical coupling in these materials. In this work, we suspend thin Cr2Ge2Te6 layers and their heterostructures, creating ferromagnetic nanomechanical membrane resonators. We probe their mechanical and magnetic properties as a function of temperature and strain by observing magneto-elastic signatures in the temperature-dependent resonance frequency near the Curie temperature, TC. We compensate for the negative thermal expansion coefficient of Cr2Ge2Te6 by fabrica…
Cellular Immunity in Adolescents and Adults following Acellular Pertussis Vaccine Administration
2007
ABSTRACT Cell-mediated immune (CMI) responses to an acellular pertussis vaccine administered to 49 subjects, a subset of participants in the National Institutes of Health-funded adult acellular pertussis vaccine efficacy trial, were evaluated and compared with antibody responses to vaccine antigens. Levels of proliferation of and cytokine secretion from lymphocytes cultured in the presence of pertussis toxin, filamentous hemagglutinin, or pertactin were measured before vaccination and 1 month and 1 year after vaccination. Statistically significant increases in lymphocyte stimulation indices and cytokine secretion were noted at both 1 month and 1 year after vaccination. Brisk pertussis antig…
Tunable Strong Coupling of Mechanical Resonance between Spatially Separated FePS3 Nanodrums
2021
Coupled nanomechanical resonators made of two-dimensional materials are promising for processing information with mechanical modes. However, the challenge for these types of systems is to control the coupling. Here, we demonstrate strong coupling of motion between two suspended membranes of the magnetic 2D material FePS$_3$. We describe a tunable electromechanical mechanism for control over both the resonance frequency and the coupling strength using a gate voltage electrode under each membrane. We show that the coupling can be utilized for transferring data from one drum to the other by amplitude modulation. Finally, we also study the temperature dependence of the coupling, and in particul…
Magnetic and electronic phase transitions probed by nanomechanical resonators
2020
The reduced dimensionality of two-dimensional (2D) materials results in characteristic types of magnetically and electronically ordered phases. However, only few methods are available to study this order, in particular in ultrathin insulating antiferromagnets that couple weakly to magnetic and electronic probes. Here, we demonstrate that phase transitions in thin membranes of 2D antiferromagnetic FePS3, MnPS3 and NiPS3 can be probed mechanically via the temperature-dependent resonance frequency and quality factor. The observed relation between mechanical motion and antiferromagnetic order is shown to be mediated by the specific heat and reveals a strong dependence of the Néel temperature of…
Controlling the anisotropy of a van der Waals antiferromagnet with light
2020
Ultrafast optical control of magnetic anisotropy in a van der Waals antiferromagnet activates a sub-THz two-dimensional magnon.
Magnetic order in 2D antiferromagnets revealed by spontaneous anisotropic magnetostriction
2023
The temperature dependent order parameter provides important information on the nature of magnetism. Using traditional methods to study this parameter in two-dimensional (2D) magnets remains difficult, however, particularly for insulating antiferromagnetic (AF) compounds. Here, we show that its temperature dependence in AF MPS$_{3}$ (M(II) = Fe, Co, Ni) can be probed via the anisotropy in the resonance frequency of rectangular membranes, mediated by a combination of anisotropic magnetostriction and spontaneous staggered magnetization. Density functional calculations followed by a derived orbital-resolved magnetic exchange analysis confirm and unravel the microscopic origin of this magnetiza…
CCDC 2068294: Experimental Crystal Structure Determination
2021
Related Article: Javier Lo��pez-Cabrelles, Samuel Man��as-Valero, In��igo J. Vito��rica-Yreza��bal, Makars S��is��kins, Martin Lee, Peter G. Steeneken, Herre S. J. van der Zant, Guillermo Mi��nguez Espallargas, Eugenio Coronado|2021|J.Am.Chem.Soc.|143|18502|doi:10.1021/jacs.1c07802
CCDC 2068293: Experimental Crystal Structure Determination
2021
Related Article: Javier Lo��pez-Cabrelles, Samuel Man��as-Valero, In��igo J. Vito��rica-Yreza��bal, Makars S��is��kins, Martin Lee, Peter G. Steeneken, Herre S. J. van der Zant, Guillermo Mi��nguez Espallargas, Eugenio Coronado|2021|J.Am.Chem.Soc.|143|18502|doi:10.1021/jacs.1c07802
CCDC 2068295: Experimental Crystal Structure Determination
2021
Related Article: Javier Lo��pez-Cabrelles, Samuel Man��as-Valero, In��igo J. Vito��rica-Yreza��bal, Makars S��is��kins, Martin Lee, Peter G. Steeneken, Herre S. J. van der Zant, Guillermo Mi��nguez Espallargas, Eugenio Coronado|2021|J.Am.Chem.Soc.|143|18502|doi:10.1021/jacs.1c07802