Fermion Condensation: a Strange Idea Successfully Explaining Behavior of Numerous Objects in Nature

Strongly correlated Fermi systems are among the most intriguing, best experimentally studied, and fundamental systems in physics. These are, however, in defiance of theoretical understanding. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature, which remains to be recognized. A theory of fermion condensation quantum phase transition, preserving the extended quasiparticles paradigm and intimately related to the unlimited growth of the effective mass as a function of the temperature, magnetic field, etc., is capable to resolve the problem. We discuss the construction of the theory and show that it delivers theoretical explanations of the vast majority of experimental results in strongly correlated systems such as heavy-fermion metals and quasi-two-dimensional Fermi systems. Our analysis is placed in the context of recent salient experimental results. Our calculations of the non-Fermi liquid behavior, the scales, and thermodynamic and transport properties are in good agreement with the heat capacity, magnetization, longitudinal magnetoresistance, and magnetic entropy obtained in remarkable measurements on the heavy-fermion metal YbRh2Si2. Using two-dimensional 3He as an example, we demonstrate that the main universal features of its experimental temperature T - density x phase diagram resemble those of the heavy-fermion metals. We propose a simple expression for the effective mass, describing all diverse experimental facts on the 3He in the unified manner and demonstrating that the universal behavior of the effective mass coincides with that observed in heavy-fermion metals.Сильнокорельованi фермi-системи є найбiльш фiзично загадковими фундаментальними та добре вивченими експериментально системами, за вiдсутностi, у той же час, їх теоретичного опису. Iдеї, якi ґрунтуються на ґратцi Кондо та квантових i термiчних флуктуацiях, використовуються для пояснення незвичної фiзики. Однак, будучи запропонованими для пояснення однiєї властивостi, цi iдеї виявилися некорисними для пояснення iнших властивостей. Такий стан речей вказує на сучасну кризу теорiї, для подолання якої нам треба буде вiдкрити невiдомий поки що фундаментальний закон. Теорiя фермiонконденсатного фазового квантового переходу, яка пiдтримує розширену парадигму квазiчастинок i допускає необмежене зростання ефективної маси як функцiї температури та напруженостi магнiтного поля, має змогу вирiшити проблему сильнокорельованих систем. Обговорено побудову теорiї i показано, що вона дозволяє описати широке коло експериментальних даних в областi таких сильнокорельованих систем, як метали з важкими фермiонами та двовимiрнi фермi-системи. Наш розгляд включає в себе опис вартих уваги експериментiв. Проведенi обчислення нефермi-рiдинної поведiнки, термодинамiчних i транспортних властивостей та вiдповiдних енергетичних шкал добре узгоджуються з даними. Цi данi вимiру теплоємностi, намагнiченостi, поздовжнього магнетоопору i магнiтної ентропiї одержано в унiкальних вимiрах на металi з важкими фермiонами YbRh2Si2. Продемонстровано, що основнi унiверсальнi властивостi фазової дiаграми температура–густина двовимiрного 3He збiгається з вiдповiдними властивостями металiв iз важкими фермiонами. Запропоновано просту формулу для ефективної маси, яка дозволяє описати унiверсальнi властивостi сильнокорельованих систем i пояснити рiзноманiтнi експериментальнi данi, зiбранi у вимiрах на 3He i металах з важкими фермiонами

Operative Treatment of Patients with Pancreatic Pseudocysts

The article presents the results of surgical treatment of patients with pancreatic pseudocysts spent in hospital surgical clinic Siberian State Medical University from 2004 to 2016. 7 (17.5%) patients underwent conservative therapy. In the early postoperative period and in the long term (18 months) the analysis of the effectiveness of different methods of surgical treatment. According to the results of the research, the operations of the internal drainage along with resection and resection-draining interventions in assessing the quality of life showed similar long-term results. In turn, these interventions have provided significantly better quality of life (p> 0.05) than external drainage operation

Energy scales and magnetoresistance at a quantum critical point

The magnetoresistance (MR) of CeCoIn_5 is notably different from that in many conventional metals. We show that a pronounced crossover from negative to positive MR at elevated temperatures and fixed magnetic fields is determined by the scaling behavior of quasiparticle effective mass. At a quantum critical point (QCP) this dependence generates kinks (crossover points from fast to slow growth) in thermodynamic characteristics (like specific heat, magnetization etc) at some temperatures when a strongly correlated electron system transits from the magnetic field induced Landau Fermi liquid (LFL) regime to the non-Fermi liquid (NFL) one taking place at rising temperatures. We show that the above kink-like peculiarity separates two distinct energy scales in QCP vicinity - low temperature LFL scale and high temperature one related to NFL regime. Our comprehensive theoretical analysis of experimental data permits to reveal for the first time new MR and kinks scaling behavior as well as to identify the physical reasons for above energy scales.Comment: 7 pages, 6 figure

Behavior of the antiferromagnetic phase transition near the fermion condensation quantum phase transition in YbRh2Si2

Low-temperature specific-heat measurements on YbRh2Si2 at the second order antiferromagnetic (AF) phase transition reveal a sharp peak at T_N=72 mK. The corresponding critical exponent alpha turns out to be alpha=0.38, which differs significantly from that obtained within the framework of the fluctuation theory of second order phase transitions based on the scale invariance, where alpha=0.1. We show that under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point leading to a violation of the critical universality of the fluctuation theory. This change of the phase transition is generated by the fermion condensation quantum phase transition. Near the tricritical point the Landau theory of second order phase transitions is applicable and gives alpha=1/2. We demonstrate that this value of alpha is in good agreement with the specific-heat measurements.Comment: 7 pages, 6 figures. to be published in Phys. Letters

Strongly correlated Fermi-systems: non-Fermi liquid behavior, quasiparticle effective mass and their interplay

Basing on the density functional theory of fermion condensation, we analyze the non-Fermi liquid behavior of strongly correlated Fermi-systems such as heavy-fermion metals. When deriving equations for the effective mass of quasiparticles, we consider solids with a lattice and homogeneous systems. We show that the low-temperature thermodynamic and transport properties are formed by quasiparticles, while the dependence of the effective mass on temperature, number density, magnetic fields, etc gives rise to the non-Fermi liquid behavior. Our theoretical study of the heat capacity, magnetization, energy scales, the longitudinal magnetoresistance and magnetic entropy are in good agreement with the remarkable recent facts collected on the heavy-fermion metal YbRh2Si2.Comment: 7 pages, 5 figure

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