Institute for Complex Systems - Sapienza - CNR

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ISC Sapienza

Home Page of José Lorenzana

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jose lorenzana at cnr it (substitute spaces by dots no accent).

Telephone:+39-0649914295 Fax: +39-064957697

José Lorenzana teachingI am a Senior Researcher and Acting Director of the Institute for Complex Systems, CNR. My main interest is complex solids intended as materials in which different phases compete producing interesting collective behavior. Competition arises because interactions and the kinetic energy contribute similarly to the energy, therefore complex solids are nor in the weak nor in the strong coupling regime which makes them difficult to treat with conventional perturbative approaches. Competition between phases often leads to gigantic responses to external perturbations which make complex solids interesting for applications.

Also, competition between long range and short range forces often leads to inhomogeneous states as in the familiar example of domain formation in ferromagnets.  In electronic systems, one interesting way to become inhomogeneous, which I have studied in the last years, is Coulomb frustrated phase separation.  Elastic forces in solids are not screened and lead to a similar phenomenology and interesting thermodynamic anomalies as in the case of the volume collapse in mixed valence compounds

Some complex solids respond magnetically to an electric field or electrically to a magnetic field. This behavior is called multiferroic. With George Sawatzky, I have developed a theory of dipole light absorption by magnetic excitations assisted by phonons. More recently I contributed to the theory of the high-Tc multiferroic effect in CuO and showed how the disorder can improve the multiferroic properties by a mechanism called order by disorder.

Goetz Seibold and I have developed a time-dependent extension of the  Gutzwiller approximation, which is a nonperturbative technique well suited to treat strongly correlated systems even when they become inhomogeneous. We have used this approach to computing collective excitations of nanostructured cuprates. Other applications have involved the magnetic phases of the Hubbard model and Auger spectroscopy.

We have not a satisfactory ab initio understanding of strongly correlated systems as we have for wideband materials. The failure in Mott systems has been put on rigorous grounds. I suggested that a non-local density functional inspired on the Gutzwiller approximation should solve some of the problems.

Barbara Mansart, Fabrizio Carbone and collaborators have shown that a high-Tc superconducting condensate can be put out of equilibrium and oscillate at a frequency given by twice the superconducting gap.  In collaboration with them, we have developed the theory of this phenomenon and a new technique called coherent charge fluctuation spectroscopy which allows identifying bosonic excitations coupled to superconducting quasiparticles potentially involved in pairing. A more recent development involves inducing Rabi oscillations in the condensate.

After many years of studying high-Tc superconductors, I have been captured by the advent of the iron age of superconductivity. In 2008, we predicted an exotic magnetic phase that competes with superconductivity and which later has been experimentally reported.  The phase diagram as a function of doping is remarkably similar to our prediction in a related compound.  More recently together with Wojciech Grochala and his group, we are exploring a possible future Silver age.


Former Postdocs

Johan Hellsvik (now researcher at Stockholm).

Valentina Brosco (now researcher at ISC).

Zujian Ying (now professor at Lanzhou University).

Gabriele Messina (now research scientist at Banca d'Italia).

Present Students

Riccardo  Piombo (PhD)

Past Students

Juan Diego Suarez-Fromm (undergraduate, 8/1996 - 12/1997, Instituto Balseiro). Now at Tecpetrol.

Daniel García (undergraduate, 8/1996 - 12/1997, Instituto Balseiro). Now at  Centro Atómico Bariloche.

Carmine Ortix (undergraduate, 9/2002 - 9/2003 and graduate, 9/2002 - 9/2003,  Universita` di Roma, “La Sapienza"). Now at  Leibniz Institute for Solid State and Materials Research, Dresden

Alessandro Attanasi (undergraduate, 5/2004 - 5/2005 and graduate, 5/2004 - 5/2005, Universita` di Roma, “La Sapienza”). Past: Nergal. Now at ISC-Sapienza.

Andrea Di Ciolo (undergraduate 6/2004-9/2005, and graduate, 6/2004-9/2005, Universita` di Roma, “La Sapienza”). Past: Goethe Universität Frankfurt. Now at Georgetown University.

Marcello Balestrieri (undergraduate 07/2010 to 01/2012. Past:t SISSA (Trieste).

Nicolò Defenu (undergraduate 03/2012-12/2012). Past: SISSA (Trieste).

Matteo Capati (undergraduate  12/2008-12/2009, Universita` di Roma, “La Sapienza”)

Antonio Tramontana (Undergraduate, 03/2014 - 12/2014, Università di Roma, “La Sapienza”) )

Nicolas Mingione (from ESPCI, Paris) (05/2017 - 07/2017, Stage at Università di Roma, “La Sapienza”)

Riccardo  Piombo (Undergraduate 10/2017-10/2018, Università di Roma, “La Sapienza”).


Via ISI.

Via Google Scholar.


Recent via CiteULike 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003

Via arXiv

Coordinated Projects

Spectroscopy of ordered and quasi-ordered complex solids (SOQCS)PDFPrintEmail
New density functionals for the electronic structure of correlated materials (NEWDFESCM)




FileDescriptionFile size
Download this file (prl69-92.pdf)Sensitivity of doping states in the copper oxides to electron lattice coupling PRL vol 69 965 (1992)424 Kb
Download this file (prl70-93.pdf)Optical conductivity of La2-xSrxCuO4 and soft electronic modesPRL vol 70 861 (1992)430 Kb
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Download this file (prl75-95.pdf)New phases in an extended Hubbard model explicitly including atomic polarizabiliPRL vol 75 4658 (1995)363 Kb
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