Electronic structure calculations of europium chalcogenides EuS and EuSe

Abstract

We have performed ab-initio self-consistent calculations on the full-potential linear muffin-tin orbital method with the local-density approximation and local spin-density approximation to investigate the structural and electronic properties of EuS and EuSe in its stable (NaCl-B1) and high-pressure phases. The magnetic phase stability was determined from the total energy calculations for both the nonmagnetic (NM) and magnetic (M) phases. These theoretical calculations clearly indicate that both at ambient and high pressures, the magnetic phase is more stable than the nonmagnetic phase. The transition pressure at which these compounds undergo the structural phase transition from NaCl-B1 to CsCl-B2 phase is calculated. The elastic constants at equilibrium in both NaCl-B1 and CsCl-B2 structures are also determined.

Structural Stabilities and Elastic Constants of EuX (X = O, S, Se, and Te) Compounds at High Pressure

“…[7] 3.33 [7] exp. 3.635 [23] 118 [4] , 91 [26] 2.2 [16] 57 [7] , 68 [13] , 77 [15] , 87 [16] 2.7 [7] , 3.79 [15] , 3.9 [16] 6.96 [13] exp.…”

“…4.213 [24] 61 ± 5 [3] B2 theory present 3.626 53 4.19 7.13 others 3.38 [15] , 3.36 [16] 101.19 [13] , 71.19 [15] , 86.3 [16] 4.55 [15] , 3.77 [16] 6.99 [13] EuSe B1 theory present 4.364 41.5 4.089 7.00 others 4.232 [12] , 4.115 [15] , 4.04 [16] 51 [7] , 52 [12] , 66 [15] , 73.4 [16] 2.6 [7] , 3.96 [15] , 4.6 [16] 6.95 [12] exp.…”

“…4.368 [25] 52 ± 5 [26] B2 theory present 3.75 45.28 4.375 7.02 others 3.54 [15] , 3.52 [16] 101.73 [12] , 59.71 [15] , 75.2 [16] 4.51 [15] , 4.56 [16] 6.98 [12] EuTe B1 theory present 4.684 32.5 4.091 7.000 others 4.529 [14] , 4.341…”

“…But it is found that the obtained elastic constants from the dierent classical molecular-dynamics simulations [811] and the dierent rst-principles calculations [1217] were not in good consistence, some were not in agreement with the experimental results [3,4]. Particularly and confusedly, the obtained elastic constants in 2007 with the FP-LMTO method in the LDA scheme [15] and in 2011 with the FP--LAPW scheme in the frame of the GGA [16] deviated from the experimental data [3,4] far away; the recent An et al [17] calculations for EuO and EuS using the (720) projector augmented plane-wave (PAW) method also did not agree well with the experimental data [3,4].…”

“…In 20082009, Gour et al [911] investigated the pressure--induced phase transitions and elastic properties of EuX (X = O, S, Se, Te) using three-body interaction potential (TBIP) approach. In rst-principles calculations, the electronic, elastic (EuS, EuSe and EuTe) and magnetic properties as well as pressure-induced phase transitions of EuX (X = O, S, Se, Te) were investigated in the recent years using the tight-binding linear mun-tin orbital method within the local-density approximation (LDA) [1214] and the full-potential linear mun-tin orbital (FP-LMTO) method within the LDA scheme [15], also LDA+U and GGA+U schemes [7] as well as the full--potential linearized-augmented plane wave (FP-LAPW) scheme in the frame of the generalized gradient approximation (GGA) [16]. The obtained transition pressures from these dierent methods were similar and were in reasonable agreement with the experimental data [3,4] except for one or two cases.…”