PAOLO POSTORINO

CURRICULUM VITAE of PAOLO POSTORINO

July 1980 Diploma of Maturità Scientifica.
May 1989 Laurea in Fisica, University of Roma Sapienza
1989 - 1990 Visiting scientist at the ISIS Spallation Neutron Source (RAL, UK) under EU project RAL/EEC ST2J-0314-C
1990 - 1993 Ph.D. Fellowship in “Condensed Matter Physics”, University of Perugia-L’Aquila
1993 – 2002 Researcher at the Engineering Faculty – Physics Dept. – University of Roma Sapienza.
July 2000 Winner of a national competition for Associate Professor.
2002-2010 Associate Professor at the Engineering Faculty – Physics Dept. – University of Roma Sapienza
Since 2010 Associate Professor at the Science Faculty – Physics Dept. – University of Roma Sapienza
In 2013 winner of the first National Scientific Qualification to function as Full Professor in Experimental Condensed Matter Physics (Professore I Fascia 02/B1 Fisica della materia sperimentale ) .

He is the group leader of the HPS (High Pressure Spectroscopy) group of the Dept. of Physics of the Univ. Sapienza which at present, consists of two Associate Professors, three Ph.D students, and 4 Master degree students. The laboratory consists of two MicroRaman spectrometers (the newest is operating in the Terahertz range) equipped with different laser sources (HeNe, Ar+, pulsed laser source tunable within the 400 nm -2600 nm wavelength range). A complete high pressure equipment (diamond anvil cells, spark eroders etc.) is available.

Responsibility, Research Projects & Research Lines
• Since 1999 responsible of a research line (C8) of the INFM.
• Since 2001-today responsible of the HPS (High-Pressure Spectroscopy) Research Group of the Physics Dept. of the University of Roma Sapienza.
• 2003-10 responsible of the Raman Group within the CRS-Coherentia (Napoli) of INFM-CNR.
• Member of the SISN (Società Italiana Spettroscopia Neutronica), INFM (Istituto Nazionale per la Fisica della Materia), INFN (Istituto Nazionale Fisica Nucleare), EHPRG (European High-Pressure Research Group).
• 2002-05 , 2008-11 , and 2013-16 Member of the International Scientific Committee of the EHPRG
• 2009-12 Member of the Panel IV for proposal evaluation of ILL (Grenoble).
• 2015 Member of the Board of CNIS (Centro di ricerca per le Nanotecnologie applicate all'Ingegneria Sapienza)
• Since 2004 member of the board (Collegio dei Docenti) first of the Material Science Ph.D., then of the Mathematical Models for Engineering, Electromagnetics and Nanosciences Ph.D. of the University of Roma Sapienza.

Research project funded (public financing):
• 1998-99 Metallization Transition in simple Molecular Systems ( INFM).
• 2000-02 Study of the charge ordering state in Manganites as a function of temperature and Pressure, (PRIN - MIUR).
• 2003-04 Local Unit Resp. High-Pressure induced transitions (PAISS - INFM).
• 2003-04 Local Unit Resp. Study of the effect of isotropic and epitassial strain on the metallization processes in Manganites by means of Raman, Infrared and X-Ray diffraction. (PRIN - MIUR)
• 2004-06 Local Unit Resp. Study the charge-localization extent induced by isotropic and epitassial strains in perovskite Manganites by means of of optical spectroscopies and diffraction techniques. (PRIN - MIUR)
• 2005-08 PRES MAG-O Project (INFN)
• 2015-2018 Underwater Tracking System (INFN)
• The research in the last years has been almost continuously funded by several "Progetti di Ateneo" for an average amount of 4-5 Keuro/year.
Research project funded (private financing) :
• 2009-11 Local Unit Resp. Chemical Control and Doping Effects in Pnictide High-temperature Superconductors (Fondazione CARIPLO).
• 2014-16 Local Unit Resp. Chemical Control and Doping Effects in Pnictide High-temperature Superconductors (Fondazione CARIPLO).

Research Activity

The research activity carried out within a research group since 1989 and since 1996 as a group leader, has focused on the following major subjects:
1) Hydrogen bonded systems: static and dynamics of bonded proton in solid and liquid hydrogen bonded systems.
2) Conductive and structural transitions: pressure induced transition in a) molecular and b) strongly correlated electron systems, weakly bonded (van der Waals, hydrogen bonded ) organic systems.
3) Spectroscopy at the nanoscale

1) Hydrogen bonded systems
The research activity in this field started during my staying at the ISIS Spallation Neutron Source (UK) and was the central argument of my Ph.D. thesis. A number of experiments were carried out using the neutron spectrometers eVS and SANDALS installed at ISIS on several H-bonded systems such as KH2PO4, H2SO4, KHCO3, H2O. Among the different results we obtained, I want to mention the first experimental reconstruction of the momentum distribution of the bonded proton along an H-bond in KHCO3 single crystals by means of epithermal neutron spectroscopy. The most important results were obtained from the study of the temperature and pressure behavior of the H-bond in liquid H2O. In particular, a neutron-diffraction study of supercritical water, appeared in Nature in 1993, showed for the first time a de-structuring of water which, above the critical point, behaves like a simple liquid. The whole of the experimental data, together with a new approach for the data analysis, depicted a novel and unexpected scenario for the evolution of the peculiar tetrahedral coordination of water, where density is the driving parameter of the system evolving from a complex to a simple fluid regime. Our results stimulated many theoretical works and still represent a bench mark to be accounted for in the more recent literature on liquid H2O.

2) Insulator to metal transition.
The Insulator to Metal Transition (IMT) has attracted a great interest since the early stage of quantum mechanical theory. Indeed, the first theoretical predictions of the existence of a high-pressure metallic hydrogen phase, described by means of a simple band-overlap mechanism, can be traced back to the early forties. Nowadays, although metallic hydrogen is still a challenging quest, IMT’s have been experimentally and theoretically investigated in a number of materials. It is clear that several microscopic interactions play a role in the charge delocalization process and that a number of external (pressure, temperature, magnetic fields ..) and internal (chemical doping, disorder, extent of the different microscopic coupling: intermolecular, electron-electron electron-phonon) parameters affect the process, depending on the given system.

a) Molecular systems
My research activity in this field was mainly focused at studying pressure-induced IMT in solid and liquid halogens. The IMT occurring in solid halogens was rather well known, since it was considered as the “classical” counterpart of the predicted and not yet experimentally achieved hydrogen IMT. Knowledge of the IMT in the fluid phase was much scarcer, although more intriguing, because of the combination of extreme pressure and temperature conditions (P=3-4 GPa and T=900 K for I2 ) required by the experiment. In I2 the IMT occurs at a pressure much lower in the fluid (3-4 GPa) than in the solid (16 GPa). Liquid I2 was then investigated using several experimental techniques (Infrared, Visible, and UV absorption spectroscopy, Raman, EXAFS) and we actually developed a specific high-temperature high-pressure experimental apparatus for each technique. The comparison of the results obtained on I2 in liquid, solid and solution environments shows the importance of the thermal induced disorder in causing the early metallization and a general model for metallic liquid halogens based on the occurrence of instantaneous percolative paths among interacting molecules was proposed. The comparison among the IMT transitions occurring in several simple liquid systems (such as Cs, Rb, Hg, and H2) led us to the idea of a sort of universal liquid at least in proximity of the IMT.

b) Strongly correlated electron systems.
In the last decades, strongly correlated electron systems have been the subject of intense research stimulated by both the remarkable technological potential for applications (colossal magneto-resistance materials (CMR), superconductors, material for electrodes for new batteries…) and the challenges for fundamental physics. In many of these systems the macroscopic properties arise from a delicate balance among several microscopic interactions which play a fundamental role in condensed matter physics (e.g. electron-electron, electron-phonon…). This cumbersome physical ground results in a complex interplay among lattice, electronic, orbital, and spin degrees of freedom of the system which makes very difficult the theoretical and experimental approaches to gain a deeper knowledge and eventually the route to material engineering.
About ten years ago, I started to work on CMR manganites (A1-xA'xMnO3 where A is a rare earth and A’ a divalent metal). The main idea was that of using several experimental tools (hydrostatic and “chemical” pressure, effective charge doping) to decouple the effects of the different interactions and, through this, to investigate CMR and the closely related paramagnetic-insulating to ferromagnetic-metallic transition. A multi-technique experimental approach was developed, owing to the strong coupling among the different degrees of freedom, and pressure and temperature dependent experiments were carried out using Raman and Infrared spectroscopies, X-ray diffraction and more recently neutron diffraction which is an efficient magnetic probe. Moreover, to treat the complexity of the underlying physical mechanisms we also developed specific theoretical models. The results of our extended experimental studies on La1-xCaxMnO3- CMR manganites enabled to obtain the first extended P-T phase diagram of a manganites, which successively has been semi-quantitatively theoretically reconstructed. The most interesting feature is that, surprisingly, a strongly P-dependent antiferromagnetic interaction, leading to a phase separated scenario at high-P and low-T, has to be taken into account also at ambient conditions. This result, later confirmed by other international groups, can clearly have a deep impact on possible attempts of application-aimed material engineering. Moreover, some of the high-P results gave us a key to the analysis of the experimental data on thin films of La1-xSrxMnO3, which enabled to establish a direct connection between the effects of epitassial strain and isotropic external pressure. Identifying this link gave access to clear recipes for films characterization. The relevance of lattice dimensionality was also investigated in layered and by-layered manganite compounds of the Ruddlesden-Popper Series (An+1MnnO3n+1) and the role of the caging effect of the A-site ion was pointed out. Recently, the dilution of magnetic interaction through Ga/Mn substitution has been investigated in LaGaxMn1-xO3 manganites. On a rather different physical ground, although with the same experimental methods, the research has been extended to other strongly correlated electron systems such as the novel superconductor MgB2 and, quite recently, the families of vanadium oxides and the so-called tri-tellurides.

3) Spectroscopy at the nanoscale
In the last years the research activity has been directed towards the study of low-dimensional systems (single few-layers materials such as MoS2, MoSe2 etc.) as well as to nano-sized materials (thin films, nanowires etc.) . In particular thanks to a collaboration with the university of Munich (TUM) and Basel most of the activity has been focused to the study of semiconductor nanowires with optical techniques (Raman and Photo Luminescence). In particular GaAs, InP nanowires have been investigated at ambient and under very high pressure. The results of this research have been published in high impact factors international journals such as Nano Letters and ACS Nano.
The possibility of plasmonic enhancement of the Raman signal using metallic nanospheres has been thoroughly investigated exploiting original auto-assembled nano-architectures as well as mixed order-disorder nano assembly. Application of this technique to specific bio-sensing has been also investigated and proposed.

The results of the research activity have been presented at many international conferences and workshops (both invited and contributed). P. Postorino is author of 150 (ISI) [175 Google-Scholar] scientific papers published in international journals, with about 2300 citations (2000 without self-citation) (ISI) on international papers and HF =25 (ISI) [Google-Scholar 2850 Citations HF=28 ].
The highest number of citations on a single paper is 220 (the second highest is 107) (ISI)

Scientific Highlights
1) The interatomic structure of H2O at supercritical temperatures.
P.Postorino, R.H. Tromp, M.A.Ricci, A.K.Soper, G.W. Neilson
Nature 366 668 (1993) (cover page)
2) Anomalous bond length expansion in liquid iodine at high pressure
U.Buontempo, A.Filipponi, D.Martinez-Garcia, P.Postorino, M.Mezouar, J.P.Itie’
Phys. Rev. Lett. 80 1912 (1998). Selected for ESRF Highlights 1997/1998 and on the INFM Highlights 1998/1999
3) Anomalous high pressure dependnce of the Jahn-Teller phonon in La0.75Ca0.25MnO3
A.Congeduti, P.Postorino, E. Caramagno, M. Nardone, A. Kumar, D.D. Sarma
Phys. Rev. Lett. 86 1251 (2001)
4) Pressure tuning of the electron-phonon coupling: the insuator-to-metal transition in manganites
P.Postorino, A.Congeduti, P. Dore, A. Sacchetti, F. Gorelli, L.Ulivi, A. Kumar, D.D. Sarma
Phys. Rev. Lett. 91 175501 (2003)
5) Far Infrared Absorption of La1-x Cax MnO3- at High Pressure
A.Sacchetti, M.Cestelli Guidi, E. Arcangeletti, A. Nucara, P. Calvani, M. Piccinini, A. Marcelli, P. Postorino
Phys. Rev. Lett. 96, 035503, (2006)
6) Pressure dependence of the charge-density-wave in in rare-earth tri-tellurides
A.Sacchetti., E.Arcangeletti, A. Perucchi, L. Baldassarre, P. Postorino, S. Lupi, N. Ru, I.R. Fisher, L. Degiorgi.
Phys. Rev. Lett. 98, 026401 (2007) (selected paper for the ELETTRA Science Update)
7) Evidence of a Pressure-Induced Metallization Process in Monoclinic VO2
E. Arcangeletti, L. Baldassarre, D. Di Castro, S. Lupi, L. Malavasi, C. Marini, A. Perucchi, P.Postorino
Phys. Rev. Lett. 98, 196406 (2007)
8) Persistence of Jahn-Teller Distortion up to the Insulator to Metal Transition in LaMnO3
M. Baldini; VV Struzhkin; AF Goncharov; P Postorino; WL Mao,
Phys Rev. Lett. 106,066402(2011)
9) A microscopic view on the Mott transition in chromium-doped V2O3.
S. Lupi, L. Baldassarre, B. Mansart, A. Perucchi, A. Barinov, P. Dudin, E. Papalazarou, F. Rodolakis, J.-P. Rueff, J.-P. Itiè, S. Ravy, D. Nicoletti, P. Postorino, P. Hansmann, N. Parragh, A. Toschi, T. Saha-Dasgupta, O. K. Andersen, G. Sangiovanni, K. Held, M. Marsi.
Nature Comm. 1, 105 (2010)
10) Pressure effects in the isoelectronic REFe0.85Ir0.15AsO system.
B. Maroni, D. Di Castro, M. Hanfland, J. Boby, C. Vercesi, M. C. Mozzati, S. Weyeneth, H. Keller, R. Khasanov, C. Drathen, P. Dore, P. Postorino, L. Malavasi.
J. Am. Chem. Soc. 133, 3252-3255 (2011)
11) Pressure Tuning of the Optical Properties of GaAs Nanowires.
I. Zardo,C. Marini, E. Uccelli, A. Fontcuberta I Morral, G. Abstreiter, P. Postorino
ACS Nano 6, 3294-3291, (2012)
10) E1(A) Electronic Band Gap in Wurtzite InAs Nanowires Studied by Resonant Raman Scattering
I. Zardo, S. Yazji, N. Hörmann, S. Hertenberger, S. Funk, S. Mangialardo, S. Morkötter, G. Koblmüller, P. Postorino, G. Abstreiter.
Nano Letters 13, 3011-3016 (2013)
13) Optical evidence of bandwidth-controlled insulator to metal transition in the cluster Mott insulator GaTa4 Se8 under pressure.
V. Ta Phuoc, C. Vaju, B. Corraze, R. Sopracase, A. Perucchi, C. Marini, P. Postorino, M. Chligui, S. Lupi, E. Janod and L. Cario
Phys. Rev. Lett. 110, 037401 (2013)
14) Origin of colossal magnetoresistance in LaMnO3 manganite
Baldini M.; Muramatsu T.; Sherafati M.; Mao HK ; Malavasi L. Postorino P. ; Satpathy S.; Struzhkin VV
PNAS 112, 10869 (2015)
15) Hexagonal Silicon Realized
Hauge, HIT; Verheijen MA; Conesa-Boj S ; Etzelstorfer T; Watzinger M; Kriegner D; Zardo I; Fasolato C; Capitani F; Postorino P; Kolling S; Li A; Assali S; Stangl J; Bakkers EPAM.
Nano Letters 15, 5855 (2015)

Academic Activity
P. Postorino has been invited to give seminars and lessons to many national and international schools and Ph.D. courses. He has been teaching the courses Fisica I, Fisica II, Fisica III (Modern Physics), Esperimentazione Fisica (Physics Laboratory), Struttura della materia con elementi di meccanica quantistica (condensed matter and quantum mechanics) at the Engineering and the Science Faculty of the University of Roma Sapienza.
Since 2004 member of the board of the Material Science Ph.D. (Collegio dei Docenti) of the University of Roma Sapienza.
Since 2005 he has been giving lectures of Raman Spectroscopy for the Ph.D. in Physics of the University of Roma Sapienza.
Since 1994 he has been (is) the supervisor of 47 Master Degree and 17 Ph.D. Physics students at the University of Roma Sapienza as well as several Bachelor's Degree students.
Some of the above students are now working (have worked) at the major foreign research institutions e.g. ETH-Zurich, Soleil-Paris, ALBA-Bacellona, ESRF-Grenoble, CSEC-Edinborough, TUM-Munich, APS-Argonne (Illinois-USA), Stanford Univ. (California-USA), TUE- Eindhoven, A