海角社区

John DiTusa

Professor of Physics, Department Chair

Ph.D., 1992 - Cornell University

海角社区 
Department of Physics & Astronomy
202K-1 and 211-B Nicholson Hall, Tower Dr.
Baton Rouge, LA 70803-4001
225-578-1195 (Chair's office) 225-578-2606-Office, 9105-Lab
ditusa@phys.lsu.edu

Research Group

Graduate Students:

Ramakanta Chapai (rchapa3@lsu.edu)

Co-Advisor: Rongying Jin

 

 

  

Postdocs:

Sunil Karna (karna1@lsu.edu)

 

 

 

Yu Li (yuli1@lsu.edu)

 

 

 

 

Former Students:

Former Postdocs:

Recent Former Undergraduate Students (Over 30 have performed research in DiTusa Laboratory):

 

Topological Spin Textures and Spin Density Wave Materials

Itinerant magnetic materials can display a wide range of interesting magnetic structures and phase transitions between different types of magnetic order. In particular, there are systems that display nanometer sized spin textures that are thought to be useful for magnetic storage applications. This research direction includes exploration of these materials to develop a fundamental understanding of the properties that drive such unusual behaviors and to search for materials that display these novel magnetic orderings.

• C. Dhital, L. DeBeer-Schmitt, D. P. Young, & J. F. DiTusa, "Unpinning the skyrmion lattice in MnSi: Effect of substitutional disorder", Phys. Rev. B 99, 024428 (2019).

• C. Dhital, L. DeBeer-Schmitt, Q. Zhang, W. Xie, D. P. Young, & J. F. DiTusa, 鈥淓xploring the origins of the Dzyalloshinski-Moriya interaction in MnSi鈥�, Phys. Rev. B 96, 214425 (2017).

 

• C. Dhital, M.A. Khan, M. Saghayezhian, W. A. Phelan, D. P. Young, R. Y. Jin, & J. F. DiTusa, "Effect of negative chemical pressure on the prototypical itinerant magnet MnSi", Phys. Rev. B 95, 024407 (2017).

 

• Y. Wu, Z. Ning, H. B. Cao, G. Cao, S. Karna, K. A. Benavides, G. T. McCandless, R. Jin, J. Y. Chan, W. A. Shelton, & J. F. DiTusa, 鈥淪pin density wave instability in a ferromagnet鈥�, Scientific Reports 8, 5225 (2018).

 

• J. H. Mendez, C. E. Ekuma, Y. Wu, B. Fulfer, J. C. Prestigiacomo, M. Jarrell, J. Moreno, W. A. Shelton, D. P. Young, P. W. Adams, A. Karki, R. Jin, J. Y. Chan, & J. F. DiTusa, 鈥淐ompeting magnetic states, disorder, and magnetic character of Fe₃Ga₄鈥�, Phys. Rev. B 91, 144409 (2015). 

• J. F. DiTusa, S. B. Zhang, K. Yamaura, Y. Xiong, J. C. Prestigiacomo, B. W. Fuller, P. W. Adams, M. I. Brickson, D. A. Browne, C. Capan, Z. Fisk, & J. Y. Chan, 鈥淢agnetic, thermodynamic, and electrical transport properties of the noncentrosymmetric B20 germanides MnGe and CoGe鈥�, Phys. Rev. B 90,144404 (2014). 

Magnetic Weyl Semimetals and Dirac Systems

Materials that display relativistic-like energy/momentum relations have attracted enormous recent interest in condensed matter physics for both fundamental and possible applications reasons. Our research focuses on identifying materials that display these types of behaviors, and to explore their consequences on the physical properties of materials.

• J. Y. Liu, J. Hu, Q. Zhang, D. Graf, H. B. Cao, S. M. A. Radmanesh, D. J. Adams, Y. L. Zhu, G. F. Cheng, X. Liu, W. A. Phelan, J. Wei, M. Jaime, F. Balakirev, D. A. Tennant, J. F. DiTusa, I. Chiorescu, L. Spinu, & Z. Q. Mao, 鈥淎 magnetic topological semimetal Sr_1鈭抷Mn_1鈭抸Sb₂ (y, z < 0.1)鈥�, Nature Materials 16, 905-910 (2017). 

• G. Cao, W. Xie, W. A. Phelan, J. F. DiTusa, & R. Jin, "Electrical anisotropy and coexistence of structural transitions and superconductivity in IrTe₂", Phys. Rev. B 95, 035148 (2017).  

Magnetic Semiconductors and Griffiths Phases

Materials that are on the verge of insulator-to-metal and paramagnetic-to-ferromagnetic or antiferromagnetic transitions are fascinating because of the effect of the nascent ordering on physical properties. We have demonstrated that the combination of critical behaviors can lead to unusual behavior and interesting physics. This includes our work on small gap semiconductors where chemical substitution can lead to metallic and magnetic states. We have discovered that the usual behavior of carrier-doped semiconductors can be amplified by the large magnetization that external fields can produce in these systems. In addition, charge carrier screening of substitution induced magnetic moments can lead to novel non-Fermi liquid behavior in these same systems. Finally, in materials where chemical substitution can lead to ferromagnetic ordering, Griffiths phases--rare regions of nascent magnetic order--can dominate the magnetic and charge carrier properties leading to unusual behaviors.

•  J. F. DiTusa, 鈥淪ilicon based Magnetic Semiconductors鈥�, Chapter in the Handbook of Spintronics, edited by Yongbing Xu, David D. Awschalom, and Junsaku Nitta, Springer Reference (Dordrecht Heidelberg New York London) (2015). 

• Figure 1. Image describes quantum critical physics of spin systems with temperature decreasing in the foreground. The green oval represents unpaired spin complexes responsible for the inelastic scattering which causes the non-Fermi liquid behavior.

  S. Guo, D. P. Young, R. T. Macaluso, D. A. Browne, N. L. Henderson, J. Y. Chan, L. L. Henry, & J. F. DiTusa, 鈥淢agnetic and thermodynamic properties of cobalt doped iron pyrite: Griffiths phase in a magnetic semiconductor鈥�, Phys. Rev. B 81, 144423 (2010). 

• S. Guo, D. P. Young, R. T. Macaluso, D. A. Browne, N. L. Henderson, J. Y. Chan, L. L. Henry, & J. F. DiTusa, 鈥淐harge transport in cobalt-doped iron pyrite鈥�, Phys. Rev. B 81, 144424 (2010). 

• N. Manyala, B.D. Ngom, A.C. Beye, R. Bucher, M. Maaza, A. Strydom, A. Forbes, A.T.C. Johnson, & J. F. DiTusa, 鈥淪tructural and magnetic properties of 蔚-Fe_1鈭抶Co_xSi thin films deposited via pulsed laser deposition鈥�, Appl. Phys. Lett. 94, 232503 (2009). 

• N. Manyala, J. F. DiTusa, G. Aeppli, & A. P. Ramirez, "Doping a semiconductor to create an unconventional metal," Nature 454, 976-980 (2008). 

• S. Guo, D. P. Young, R. T. Macaluso, D. A. Browne, N. L. Henderson, J. Y. Chan, L. L. Henry, & J. F. DiTusa, "Discovery of the Griffiths phase in the itinerant magnetic semiconductor Fe_1-xCo_xS₂," Phys. Rev. Lett. 100, 017209 (2008). 

• F. P. Mena, J. F. DiTusa, D. van der Marel, G. Aeppli, D. P. Young, A. Damascelli, & J. A. Mydosh, 鈥淪uppressed reflectivity due to spin-controlled localization in a magnetic semiconductor鈥�, Phys. Rev. B. 73, 085205 1-7 (2006). 

• N. Manyala, Y. Sidis, J. F. DiTusa, G. Aeppli, D. P. Young, & Z. Fisk, 鈥淟arge anomalous Hall effect in a silicon-based magnetic semiconductor鈥�, Nature Materials 3, 255-262 (2004). 

• N. Manyala, Y. Sidis, J. F. DiTusa, G. Aeppli, D. P. Young, & Z. Fisk, 鈥滿agnetoresistance from quantum interference effects in ferromagnets鈥�, Nature 404, 581-584 (2000); and 408, 616 (2000). 

• G. Aeppli & J. F. DiTusa, 鈥漊ndoped and doped FeSi or how to make a heavy fermion metal with three of the most common elements鈥�, Materials Science and Engineering B63, 119-124 (1999). 

• J. F. DiTusa, K. Friemelt, E. Bucher, G. Aeppli, & A. P. Ramirez, 鈥滺eavy fermion metal鈥揔ondo insulator transition in FeSi_1鈭抶Al_x鈥�,&苍产蝉辫;Phys. Rev. B 58, 10288-10301 (1998). 

• J. F. DiTusa, K. Friemelt, E. Bucher, G. Aeppli, & A. P. Ramirez, 鈥滿etal-Insulator Transition in the Kondo Insulator FeSi and Classic Semiconductors Are Similar鈥�, Phys. Rev. Lett. 78, 2831-2834 (1997); and 78, 4309 (1997). 

• K. Friemelt, J.F. DiTusa, E. Bucher, & G. Aeppli, 鈥淐oulomb interactions in Al doped FeSi at low temperatures鈥�, Annalen der Physik 5, 175-183 (1996). 

• Z. Schlesinger, Z. Fisk, Hai-Tao Zhang, M. B. Maple, J. F. DiTusa, & G. Aeppli, 鈥淯nconventional charge gap formation in FeSi鈥�, Phys. Rev. Lett. 71, 1748-17501 (1993). 

Quantum Critical Behavior

We make use of the ability to tune condensed matter systems so that they are in proximity to a zero-temperature phase transition to explore quantum critical behavior. Here, the quantum fluctuations dominate the thermal fluctuations leading to unusual behaviors including unconventional superconductivity.

• R. G. Goodrich, C. Capan, A. D. Bianchi, Z. Fisk, J. F. DiTusa, I. Vekhter, D. P. Young, L. Balicas, Y-J. Yo, T. Murphy, J. Y. Cho, & J. Y. Chan, 鈥淪C-to-AFM transition in CeCo(In_1鈭抶Cd_x)₅: de Haas-van Alphen measurements鈥�, J. Phys: Conf. Ser. 273, 012113 (2011). 

• C. Capan, Y. J. Jo, L. Balicas, R. G. Goodrich, J. F. DiTusa, I. Vekhter, T. P. Murphy, A. D. Bianchi, L. D. Pham, J. Y. Cho, J. Y. Chan, D. P. Young, & Z. Fisk, "Fermi surface evolution through a heavy fermion superconductor-to-antiferromagnet transition: de Haas-van Alphen effect in Cd substituted CeCoIn₅," Phys. Rev. B 82, 035112 (2010) [Editors鈥� suggestion].

• J. F. DiTusa, R. G. Goodrich, N. Harrison, & E. S. Choi, "Fermi surface of Cr_1-xV_x across the quantum critical point," Phys. Rev. B 82, 075114 (2010).

• C. Capan, L. Balicas, T.P. Murphy, E.C. Palm, R. Movshovich,D. Hall, S.W. Tozer, M.F. Hundley, E.D. Bauer, J.D. Thompson, J. L. Sarrao, J. F. DiTusa, R. G. Goodrich, & Z. Fisk, 鈥淯nusual metamagnetism in CeIrIn₅鈥�, Phys. Rev. B 80, 094518 (2009).

• C. Capan, R. G. Goodrich, J. F. DiTusa, L. Balicas, Y. J. Jo, T. P. Murphy, E. C. Palm, R. Movshovich, E. D. Bauer, M. F. Hundley, J. D. Thompson, J. L. Sarrao, D. Hall, & S. W. Tozer, 鈥淢etamagnetism in CeIrIn₅: Magnetoresistance and dHvA investigation鈥�, Physica B - Condensed Matter 403, 797-799 (2008).

• C. Capan, S. Singh, S. Wirth, M. Nicklas, H. Lee, Z. Fisk, J. F. DiTusa, & F. Steglich, 鈥淣ew hints on the origin of quantum criticality in CeCoIn₅: A Hall effect study鈥�, Physica B 403 1290-1292 (2008).

• C. Capan, S. Singh, S. Nair, M. Nicklas, H. Lee, J. F. DiTusa, Z. Fisk, S. Wirth, & F. Steglich, 鈥淐rossover from Landau Fermi liquid to non-Fermi liquid behavior: Indications from Hall measurements on CeCoIn₅鈥�, Physica C 460 678-679 (2007).

• S. Singh, C. Capan, M. Nicklas, M. Rams, A. Gladun, H. Lee, J. F. DiTusa, Z. Fisk, F. Steglich, & S. Wirth, 鈥淧robing the quantum critical behavior of CeCoIn₅ via Hall effect measurements鈥�, Phys. Rev. Lett. 98, 57001 1-4 (2007).

• B. Bucher, Z. Schlesinger, D. Mandrus, Z. Fisk, J. Sarrao, J. F. DiTusa, C. S. Ogelsby, G. Aeppli, & E. Bucher, 鈥淐harge Dynamics of Ce Based Compounds: Connection between the Mixed Valent and Kondo Insulator States鈥�, Phys. Rev. B 53, R2948-R2951 (1996). 

• Z. Fisk, J. L. Sarrao, J. D. Thompson, D. Mandrus, M. F. Hundley, A. Miglori, B. Bucher, Z. Schlesinger, G. Aeppli, E. Bucher, J. F. DiTusa, C. S. Ogelsby, H-R. Ott, P. C. Canfield, & S. E. Brown, 鈥淜ondo Insulators鈥�, Physica B 206 & 207, 798-803 (1995). 

• G. Aeppli, Z. Fisk, & J. F. DiTusa, 鈥淎re Kondo Insulators Simply Insulators?鈥�, Proceedings of the Los Alamos Workshop on Strongly Correlated Fermi Systems鈥�, Springer鈥揤erlag, New York (1994). 

Superconductivity

We have discovered unconventional superconducting states in materials that are highly layered, nearly two-dimensional and in materials that have non-centrosymmetric crystal structures.

• M. A. Khan, D. E. Graf, D. Browne, I. Vekhter, J. F. DiTusa, W. Adam Phelan, & D. P. Young, 鈥淨uantum oscillations and a non-trivial Berry phase in the noncentrosymmetric topological superconductor candidate BiPd鈥�,&苍产蝉辫;Phys. Rev. B 99, 020507 (2019).

• S. Guo, D. P. Young, P. W. Adams, X. S. Wu, J. Y. Chan, & J. F. DiTusa, "Dimensional crossover in the electrical and magnetic properties of the layered LaSb₂ superconductor under pressure: The role of phase fluctuations", Phys. Rev. B 83, 174520 (2011).

• J. F. DiTusa, V. Guritanu, S. Guo, D. P. Young, P. W. Adams, R. G. Goodrich, J. Y. Chan, & D. van der Marel, 鈥淥ptical conductivity and superconductivity in LaSb₂鈥�, J. Phys: Conf. Ser. 273, 012151 (2011).

• J. Y. Chan, F. R. Fronczek, D. P. Young, J. F. DiTusa, & P. W. Adams, "Synthesis, Structure, and Superconductivity in Be_1.09B₃"J. Sol. St. Chem. 163, 385-389 (2002).

Mechanisms for Magnetoresistance

Unusually large, linear in field, magnetoresistance was discovered in highly layered LaSb₂ whose origins are as of yet unexplained. We have explored the electronic structure and high magnetic field behaviors of the compound to discover its origins.

• R. G. Goodrich, D. Browne, R. Kurtz, D. P. Young, J. F. DiTusa, P. W. Adams, & D. Hall, 鈥淒e Haas - van Alphen measurements of the electronic structure of LaSb₂鈥�, Phys. Rev. B 69, 125114 1-4 (2004).

• D. P. Young, R. G. Goodrich, J. F. DiTusa, S. Guo, & P. W. Adams, 鈥淗igh magnetic field sensor using LaSb₂鈥�, Appl. Phys. Lett. 82, 3713-3715 (2003).

• V. Yu. Butko, J. F. DiTusa, & P. W. Adams, 鈥淭enfold Magnetoconductance in a Nonmagnetic Metal Film鈥�, Phys. Rev. Lett. 85, 162-165 (2000).

• V. Yu. Butko, J. F. DiTusa, & P. W. Adams, 鈥滳oulomb gap: How a Metal Film Becomes an Insulator鈥�, Phys. Rev. Lett. 84, 1543-1546 (2000).

• K. Lane, J. F. DiTusa, M. Park, M. S. Isaacson, & J. M. Parpia, 鈥淓lectron Heating Experiments Below the Spin Glass Resistance Maximum鈥�, J. Low Temp. Phys. 93, 7-14 (1993).

• J. F. DiTusa, J. M. Parpia, & J. M. Phillips, 鈥淨uantum Transport in Ultrathin CoSi₂ 贰辫颈迟补虫颈补濒&苍产蝉辫;贵颈濒尘蝉鈥�, Appl. Phys. Lett. 57, 452-454 (1990).

• J. F. DiTusa, J. M. Parpia, & J. M. Phillips, 鈥淟ow Temperature Transport in Epitaxial CoSi₂&苍产蝉辫;贵颈濒尘蝉鈥�, Physica B 165 & 166, 863-864 (1990).

Quantum Spin Systems

Insulating, low dimensional spin systems are of great interest because of their inherent quantum response. We have investigated one such system where effectively one-dimensional spin chains with S=1 Ni²⁺ ions can be controlled through chemical substitution. This has allowed us to investigate the effect of both reducing the chain lengths and creating a large population of chain-end excitations and in creating hole carriers. Informative inelastic neutron scattering experiments were carried out to explore the changes to the excitation spectrum caused by these disruptions to the Haldane ground state.

• G. Y. Xu, C. Broholm, Y. A. Soh, G. Aeppli, J. F. DiTusa, Y. Chen, M. Kenzelmann, C.D. Frost, T. Ito, K. Oka, & H. Takagi, 鈥淢esoscopic phase voherence in a quantum spin fluid鈥�, Science 317, 1049-1052 (2007).

• M. Kenzelmann, G. Xu, I. A. Zaliznyak, C. Broholm, J. F. DiTusa, G. Aeppli, T. Ito, K. Oka, & H. Takagi, 鈥淪tructure of end states for a Haldane spin chain鈥�, Phys. Rev. Lett. 90, 087202 1-4 (2003); and 90, 109902.

• G. Xu, G. Aeppli, M. E. Bisher, C. Broholm, J. F. DiTusa, C. D. Frost, T. Ito, K. Oka, R. L. Paul, H. Takagi, & M. M. J. Treacy, 鈥淗oles in a Quantum Spin Liquid鈥�, Science 289, 419-422 (2000).

• G. Aeppli, C. Broholm, J. F. DiTusa, S. M. Hayden, S. H. Lee, T. E. Mason, H. A. Mook, K. Oka, T. G. Perring, A. Schroder, H. Takagi, & G. Xu, 鈥滿agnetic Coherence in the Transition Metal Oxides鈥�, Physica B 237, 30-35 (1997).

• G. Xu, J. F. DiTusa, T. Ito, K. Oka, H. Takagi, C. Broholm, & G. Aeppli, 鈥淵₂BaNiO₅: A Nearly Ideal Realization of the S=1 Heisenberg Chain with Antiferromagnetic Interactions鈥�,&苍产蝉辫;Phys. Rev. B 54, R6827-R6830 (1996).

• C. Broholm, G. Aeppli, S.-H. Lee, W. Bao, & J. F. DiTusa, 鈥淪trong Magnetic Fluctuations in Transition Metal Oxides鈥�, J. Appl. Phys. 79, 5023-5028 (1996).

• G. Aeppli, W. Bao, C. Broholm, S.-W. Cheong, P. Dai, S. M. Hayden, T. E. Mason, H. A. Mook, T. G. Perring, & J. F. DiTusa, 鈥淢agnetic Correlations in Doped Transition鈥揗etal Oxides鈥�, Spectroscopy of Mott Insulators and Correlated Metals, Springer Series in Solid State Sciences, 119, Edited by A. Fujimori and Y. Tokura, Springer Verlag, Berlin, 205-212 (1995).

• J. F. DiTusa, S-W. Cheong, J.-H. Park, G. Aeppli, C. Broholm, & C. T. Chen, 鈥淢agnetic and Charge Dynamics in a Doped One鈥揇imensional Transition Metal Oxide鈥�, Phys. Rev. Lett. 73, 1857-1860 (1994).

Other Publications

• M. Li, S. L. De Rooy, D. K. Bwambok, B. El-Zahab, J. F. DiTusa, & I.M.Warner, 鈥淢agnetic chiral liquids derived from amino acids鈥�, Chem. Comm. 45, 6922-6924 (2009).

• J. F. DiTusa, K. Lin, M. S. Isaacson, & J. M. Parpia, 鈥淩ole of Phonon Dimensionality on Electron鈥揚honon Scattering Rates鈥�, Phys. Rev. Lett. 68, 1156-1159 (1992).

• J. F. DiTusa, K. Lin, M. Park, M. S. Isaacson, & J. M. Parpia, 鈥淔inite鈥揝ize Effects in the Low鈥揟emperature Resistivity of CuCr Films鈥�, Phys. Rev. Lett. 68, 678-681 (1992).

• J. F. DiTusa, Y. K. Kwong, K. Lin, M. Park, M. S. Isaacson, & J. M. Parpia, 鈥淭he Electron鈥揚honon Scattering Rate in Thin Free鈥揝tanding Metallic Films鈥�, Proceedings of the Seventh International Conference on Phonon Scattering in Condensed Matter, 143-144 Springer鈥揤erlag, New York (1992).

• V. Kotsubo, J. F. DiTusa, T. Hall, R. Mihailovich, & J. M. Parpia, 鈥淩eduction of the Superfluid Fraction of ³He in Sintered Silver鈥�, Jpn. J. Appl. Phys. 26 143-144 (1987).

• R. E. Warner, J. F. DiTusa, A. Nadasen et al. 鈥淭he Mechanism of the ⁷Li(d,2伪)n Reaction From E_d = 3 to 15 MeV鈥�, Nuclear Physics A470, 339-348 (1987).

Curriculum Vitae

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